Background A significant proportion of patients with ST-elevation myocardial infarction (STEMI) present without cardiac symptoms of chest pain. Such presentations potentially affect the care they receive and ultimately affect these patients’ short and long-term outcomes. We analysed a national acute myocardial infarction (AMI) registry to characterise the demographics, processes of care and outcomes of non-chest pain (NCP) STEMI presentations. Methods Retrospective data for all STEMI cases from 2007 to 2020 were analysed from the Singapore Myocardial Infarction Registry. Cases which happened during inpatient and interfacility transfers were excluded. Univariable and multivariable logistic models were used to identify factors associated with NCP presentation. Cox proportional hazard models were constructed to investigate the prognostic influence of NCP on short-term and long-term mortality outcomes. ORs and HRs were calculated along with their 95% CI. Results Among 21 858 patients with first-onset STEMI, 12.6% presented with NCP. These patients were older, more likely to be women and Chinese and had never smoked. The prevalence of diabetes and hypertension was also higher. These patients were also less likely to present with other possible cardiac symptoms of AMI, such as dyspnoea and diaphoresis. They were less likely to receive percutaneous coronary intervention (36% vs 77%) and had longer door-to-balloon times (100 min vs 70 min). After adjusting for differences in baseline risk factors and clinical characteristics, NCP presentation was associated with a higher risk of all-cause mortality at 30 days (HR 2.93, 95% CI 2.62 to 3.28), 1 year (HR 2.80, 95% CI 2.56 to 3.06), 5 years (HR 2.47, 95% CI 2.30 to 2.66) and 10 years (HR 2.31, 95% CI 2.16 to 2.46). Conclusion After adjusting for baseline risk factors and treatments received, NCP presentation was still independently associated with worse survival outcomes. Further research is required to risk-stratify these patients and address the suboptimal treatment rates and outcomes.

Introduction:Acute coronary syndrome (ACS) carries a high early risk of recurrent events, yet time-to-target low-density lipoprotein cholesterol (LDL-C) is often prolonged, and goal attainment is suboptimal in real-world practice. The authors aimed to develop expert consensus recommendations for post-ACS lipid management in Singapore, focusing on LDL-C targets, pharmacotherapy, escalation strategies, and implementation tools to improve adherence and reduce therapeutic inertia. Method:A modified Delphi methodology was employed with a panel of 10 members. Evidence was synthesised from guidelines, randomised trials, metaanalyses, and observational studies. Thirty-two statements were drafted across 5 domains (LDL-C targets; timing/ monitoring; pharmacotherapy; special populations; implementation/adherence/health-system strategies) and rated anonymously on a 5-point Likert scale. Consensus thresholds were defined as high (≥75% concordant), moderate (55-74%), and low (<55%). Results:After the final round, 30 of 32 statements achieved high consensus, and 2 received low consensus. Key agreements included measuring lipids within 24 hours of admission and retesting at 4-6 weeks, early initiation of high-intensity statins, and upfront combination therapy with statin + ezetimibe when monotherapy is unlikely to achieve the goals. Consideration of a proprotein convertase subtilisin/kexin type 9 inhibitor at discharge was recommended if LDL-C remained >1.4 mmol/L. Special considerations included older adults, familial hypercholesterolaemia, lower statin adherence among women, and the role of lipoprotein(a). The panel recommended adopting objective metrics, integrating electronic health record prompts, and developing localised pathways to harmonise care transitions. Conclusion:The consensus recommendations provide a tailored approach for Singapore, emphasising early action, proactive escalation, and systems-level interventions to improve post-ACS outcomes.

BACKGROUND Standard modifiable risk factors (SMuRFs) are associated with increased risk of acute myocardial infarction (AMI). Patients with AMI in the absence of standard modifiable risk factors (SMuRF-less) have demonstrated excess mortality. OBJECTIVES The study aims to forecast trends in prevalence and case fatality of SMuRF-less AMI in Singapore and United Kingdom. METHODS Data from the Singapore Myocardial Infarction Registry and the UK Myocardial Ischemia National Audit Project were used to construct Poisson regression models to predict the prevalence and case fatality rate of SMuRF-less AMI from 2025 to 2040. RESULTS From 2025 to 2040, SMuRF-less AMI cases are expected to contribute to larger proportions of total AMI cases in Singapore (5.8% [95% CI: 5.2%-6.4%] to 8.5% [95% CI: 6.2%-10.8%]) and United Kingdom (13.8% [95% CI: 13.0%-14.6%] to 16.9% [95% CI: 15.1%-18.7%]). The proportion of SMuRF-less AMI mortality of the total AMI mortality is set to decrease in the United Kingdom (11.3% [95% CI: 10.5%-12.1%] to 9.5% [95% CI: 7.7%-11.4%]), but increase in Singapore (6.3% [95% CI: 5.7%-6.9%] to 13.3% [95% CI: 10.9%-15.6%]). Men continue to bear the majority of SMuRF-less AMI prevalence, with the most rapid rise in young adults in Singapore (8.1%; 95% CI: 7.5%-8.7%) and middle-aged adults in the United Kingdom (2.3%; 95% CI: 1.5%-3.1%). The increase in SMuRF-less AMI prevalence is set to be more rapid in the overweight/obesity population (3.9%; 95% CI: 3.3%-4.5%). CONCLUSIONS By 2040, SMuRF-less AMI will expand to a larger proportion of the AMI census in Western and Eastern populations. SMuRF-less AMI vulnerability will shift toward a younger, male-dominant demographic, with overweight/ obesity as a dominant risk factor. (JACC Asia. 2026;6:910-925) (c) 2026 The Authors. Published by Elsevieron behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Background Standard modifiable risk factors (SMuRFs) are associated with increased risk of acute myocardial infarction (AMI). Patients with AMI in the absence of standard modifiable risk factors (SMuRF-less) have demonstrated excess mortality. Objectives The study aims to forecast trends in prevalence and case fatality of SMuRF-less AMI in Singapore and United Kingdom. Methods Data from the Singapore Myocardial Infarction Registry and the UK Myocardial Ischemia National Audit Project were used to construct Poisson regression models to predict the prevalence and case fatality rate of SMuRF-less AMI from 2025 to 2040. Results From 2025 to 2040, SMuRF-less AMI cases are expected to contribute to larger proportions of total AMI cases in Singapore (5.8% [95% CI: 5.2%-6.4%] to 8.5% [95% CI: 6.2%-10.8%]) and United Kingdom (13.8% [95% CI: 13.0%-14.6%] to 16.9% [95% CI: 15.1%-18.7%]). The proportion of SMuRF-less AMI mortality of the total AMI mortality is set to decrease in the United Kingdom (11.3% [95% CI: 10.5%-12.1%] to 9.5% [95% CI: 7.7%-11.4%]), but increase in Singapore (6.3% [95% CI: 5.7%-6.9%] to 13.3% [95% CI: 10.9%-15.6%]). Men continue to bear the majority of SMuRF-less AMI prevalence, with the most rapid rise in young adults in Singapore (8.1%; 95% CI: 7.5%-8.7%) and middle-aged adults in the United Kingdom (2.3%; 95% CI: 1.5%-3.1%). The increase in SMuRF-less AMI prevalence is set to be more rapid in the overweight/obesity population (3.9%; 95% CI: 3.3%-4.5%). Conclusions By 2040, SMuRF-less AMI will expand to a larger proportion of the AMI census in Western and Eastern populations. SMuRF-less AMI vulnerability will shift toward a younger, male-dominant demographic, with overweight/obesity as a dominant risk factor.

INTRODUCTION:Stress hyperglycemia is associated with adverse outcomes in ST-elevation myocardial infarction (STEMI), but whether age influences its development or prognostic significance remains unclear. We examined the association between age and stress hyperglycemia and whether age modifies its relationship with mortality. METHODOLOGY:We studied non-diabetics with first-onset STEMI from the Singapore Myocardial Infarction Registry (SMIR) (2008-2020). The stress hyperglycemia ratio (SHR) was calculated as random plasma glucose (mmol/L)/[1.59 × HbA1c (%) - 2.59], with stress hyperglycemia defined as SHR ≥1.51. Logistic regression identified factors independently associated with stress hyperglycemia. Restricted cubic splines assessed non-linearity between age and odds of stress hyperglycemia. Multivariate Cox regression evaluated associations with 30-day, 1-year, and 10-year all-cause mortality. Analyses were stratified by age and sex. RESULTS:Among 8,779 patients, 1,718 (19.6%) developed stress hyperglycemia. Patients with stress hyperglycemia were older and more likely to present with advanced heart failure. Increasing age was independently associated with higher odds of stress hyperglycemia, with no evidence of non-linearity. Stress hyperglycemia conferred higher short- and long-term mortality across all age groups, although the relative association attenuated with advancing age (P for interaction <0.001). Similar trends were observed in both sexes. CONCLUSION:In non-diabetic patients with first-onset STEMI, the likelihood of stress hyperglycemia increased with age. However, stress hyperglycemia was associated with the greatest risk of mortality in younger patients.

BACKGROUND:Compared with patients who develop ST-segment-elevation myocardial infarction (STEMI) outside the hospital and present at the emergency department (outpatient-onset), patients with inpatient-onset STEMI may paradoxically experience a poorer prognosis due to underlying disease, despite the apparent immediate access to acute health care services. METHODS:Patients with first-onset STEMI who underwent percutaneous coronary intervention (PCI) in the Singapore Myocardial Infarction Registry (2007-2020) were included. For patients with inpatient-onset STEMI, the recognition-to-balloon time was measured from symptom onset to PCI. For outpatient-onset STEMI, the recognition-to-balloon time was defined as the sum of the symptom-to-door and door-to-balloon time. Logistic regression was used to identify factors associated with delayed PCI after inpatient-onset STEMI. Cox regression was used to assess 30-day, 1-year, 5-year, and 10-year all-cause and cardiovascular mortality. RESULTS:A total of 19 149 patients, 17 659 (92.2%) outpatient-onset and 1595 (7.8%) inpatient-onset, were included. The median follow-up duration was 6.91 years. Patients with inpatient-onset STEMI were older, more frequently women, nonsmokers, more likely to have comorbidities, less likely to present with typical STEMI symptoms, and more likely to experience delays in PCI than patients with outpatient-onset STEMI within the hospital setting. The independent predictors of delayed PCI for inpatient-onset STEMI were age ≥65 years, diabetes, breathlessness at presentation, and Killip class III. After adjustment for differences in baseline and clinical characteristics, inpatient-onset STEMI was associated with significantly greater 1-year, 5-year, and 10-year all-cause mortality (1-year hazard ratio [HR], 1.27 [95% CI, 1.13-1.43]; 5-year HR, 1.27 [95% CI, 1.13-1.43]). There was no difference in 30-day all-cause or short-/long-term cardiovascular mortality. CONCLUSIONS:Inpatient-onset STEMI was linked to an increased long-term risk of all-cause mortality compared with outpatient-onset STEMI despite a shorter recognition-to-balloon time.

BACKGROUND:Guideline-directed medical therapies (GDMTs), such as beta-blockers, antiplatelet drugs, lipid-lowering drugs, and renin-angiotensin system agents, have been associated with reduced risk of mortality after acute myocardial infarction (AMI). However, this survival benefit conferred by GDMTs in nonagenarians and centenarians (≥ 90 years old) is not well-defined. METHODS:We investigated restricted mean survival times of patients ≥ 90 years of age with first-onset AMI treated with GDMTs from 2007 to 2020 in the Singapore Myocardial Infarction Registry. Primary analyses involved stratification by number of GDMTs prescribed at discharge, with derivation of pairwise restricted mean survival ratios free from all-cause mortality at 1, 3, and 5 years. Secondary analyses evaluated individual GDMTs within combinations of 1-3 GDMTs. RESULTS:The analysis included 3264 patients: 0 GDMTs (561 patients, 17.2%), 1-2 GDMTs (1294 patients, 39.6%), 3 GDMTs (904 patients, 27.7%), and 4 GDMTs (505 patients, 15.5%), with a median follow-up duration of 5.71 years. Patients who received 4 GDMTs at discharge were younger, had more comorbidities, were more likely to be smokers, and were more likely to have undergone percutaneous coronary intervention than those prescribed fewer GDMTs. A greater number of GDMT classes at discharge was associated with longer survival free from all-cause mortality at 1, 3, and 5 years. Each drug class within combinations of 1-3 GDMTs was associated with significant survival benefit at all time points, except for beta-blockers. CONCLUSIONS:Prescription of any number of GDMTs to nonagenarians and centenarians after first-onset AMI is associated with significant survival benefit.

An electrocardiogram (ECG) is the mainstay of cardiac evaluation available in primary care, after which assessment in relation to clinical symptoms and signs is made by family physicians to assess the patients holistically. Subsequently, based on this clinical evaluation, patients may then be referred for tertiary review at a cardiology department or managed in primary care. In Singapore, ECG abnormalities found in asymptomatic patients may require a specialist review and thus make up a substantial number of patients referred by primary care physicians from public healthcare polyclinics to cardiology outpatient clinics. Some of these patients may be clinically managed in primary care with no further evaluation necessary, yet others may require a non-urgent or expedited review.

INTRODUCTION:Left bundle branch area (LBBA) pacing (LBBAP) has been proposed as an alternative therapy option in patients indicated for cardiac pacing to treat bradycardia or heart failure. The aim of the study was to evaluate the safety and effectiveness of LBBAP in patients implanted with a Tendril 2088 stylet-driven lead. METHODS:The international retrospective data collection registry included 11 sites from 5 countries globally. Patients with attempted implants of the Tendril lead in the LBBA were followed for at least 6 months post the implant attempt. The primary safety and efficacy endpoints were freedom from LBBAP lead-related serious adverse events and the composite of LBBA capture threshold of ≤2.0 V and R-wave amplitudes ≥5 mV (or ≥value at implant), respectively. RESULTS:Of 221 patients with attempted implants of the Tendril 2088 lead in the LBBA, 91.4% (202/221) had successful implants for LBBAP. Regardless of the LBBAP implant success, all patients were followed for at least 6 months (8.7 ± 7.3 months). Baseline characteristics: 44% female, 84% ≥65 years old, 34% coronary artery disease, and 86% of primary indications for pacemaker implant. Both primary safety and effectiveness endpoints were met (freedom from LBBAP lead-related serious adverse device effects of 99.5% and electrical performance composite success rate of 93%). The capture thresholds in LBBAP at implant and 6 months were 0.8 ± 0.3 V@0.4 ± 0.1 ms and 0.8 ± 0.3 V@0.4 ± 0.1 ms. The rate of patients with capture threshold rise ≥1 V was 1.5% through 6 months. The R-wave amplitudes in LBBAP at implant and 6 months were 9.3 ± 3.2 mV and 10.6 ± 3.0 mV. CONCLUSIONS:This large multicenter study demonstrates that the stylet-driven Tendril™ STS 2088 lead is safe and effective for LBBAP with high success and low complication rates.

ABSTRACT:Cardiac pacing has been an established therapy for bradyarrhythmia due to sinus or atrioventricular nodal disease since the 1950s. However, contemporary studies have shown that conventional right ventricular pacing (RVP) causes electromechanical dyssynchrony, which can lead to atrial fibrillation, heart failure and even death. Recently, the push for a more physiological cardiac pacing has seen a revival in the utilisation and development of conduction system pacing (CSP). There has been a shift towards adopting His bundle pacing (HBP) or left bundle branch area pacing (LBBaP) in bradycardia patients worldwide and in Singapore. This review serves to outline the electrophysiological concepts behind CSP and illustrate the different paced electrocardiogram characteristics of HBP, LBBaP and RVP to aid understanding of this revolutionary pacing approach among medical practitioners in Singapore.

BACKGROUND:Cardiocerebral infarction (CCI), which is concomitant with acute myocardial infarction (AMI) and acute ischemic stroke (AIS), is a rare but severe presentation. However, there are few data on CCI, and the treatment options are uncertain. We investigated the characteristics and outcomes of CCI compared with AMI or AIS alone. METHODS:We performed a retrospective cohort study of 120 531 patients with AMI and AIS from the national stroke and AMI registries in Singapore. Patients were categorized into AMI only, AIS only, synchronous CCI (same-day), and metachronous CCI (within 1 week). The primary outcome was all-cause mortality, and the secondary outcome was cardiovascular mortality. The mortality risks were compared using Cox regression. Multivariable models were adjusted for baseline demographics, clinical variables, and treatment for AMI or AIS. RESULTS:Of 127 919 patients identified, 120 531 (94.2%) were included; 74 219 (61.6%) patients had AMI only, 44 721 (37.1%) had AIS only, 625 (0.5%) had synchronous CCI, and 966 (0.8%) had metachronous CCI. The mean age was 67.7 (SD, 14.0) years. Synchronous and metachronous CCI had a higher risk of 30-day mortality (synchronous: adjusted HR [aHR], 2.41 [95% CI, 1.77-3.28]; metachronous: aHR, 2.80 [95% CI, 2.11-3.73]) than AMI only and AIS only (synchronous: aHR, 2.90 [95% CI, 1.87-4.51]; metachronous: aHR, 4.36 [95% CI, 3.03-6.27]). The risk of cardiovascular mortality was higher in synchronous and metachronous CCI than AMI (synchronous: aHR, 3.03 [95% CI, 2.15-4.28]; metachronous: aHR, 3.41 [95% CI, 2.50-4.65]) or AIS only (synchronous: aHR, 2.58 [95% CI, 1.52-4.36]; metachronous: aHR, 4.52 [95% CI, 2.95-6.92]). In synchronous CCI, AMI was less likely to be managed with PCI and secondary prevention medications (P<0.001) compared with AMI only. CONCLUSIONS:Synchronous CCI occurred in 1 in 200 cases of AIS and AMI. Synchronous and metachronous CCI had higher mortality than AMI or AIS alone.

IntroductionObesity is an important risk factor for acute myocardial infarction (AMI), but the interplay between metabolic health and obesity on AMI mortality has been controversial. In this study, we aimed to elucidate the risk of short- and long-term all-cause mortality by obesity and metabolic health in AMI patients using data from a multi-ethnic national AMI registry.MethodsA total of 73,382 AMI patients from the national Singapore Myocardial Infarction Registry (SMIR) were included. These patients were classified into four groups based on the presence or absence of metabolic diseases, diabetes mellitus, hyperlipidaemia, and hypertension, and obesity: (1) metabolically-healthy-normal-weight (MHN); (2) metabolically-healthy-obese (MHO); (3) metabolically-unhealthy-normal-weight (MUN); and (4) metabolically-unhealthy-obese (MUO).ResultsMHO patients had reduced unadjusted risk of all-cause in-hospital, 30-day, 1-year, 2-year, and 5-year mortality following the initial MI event. However, after adjusting for potential confounders, the protective effect from MHO on post-AMI mortality was lost. Furthermore, there was no reduced risk of recurrent MI or stroke within 1-year from onset of AMI by the MHO status. However, the risk of 1-year mortality was higher in female and Malay AMI patients with MHO compared to MHN even after adjusting for confounders.ConclusionIn AMI patients with or without metabolic diseases, the presence of obesity did not affect mortality. The exception to this finding were female and Malay MHO who had worse long-term AMI mortality outcomes when compared to MHN suggesting that the presence of obesity in female and Malay patients may confer worsened outcomes.

Dear Sir, Patients with implantable cardioverter defibrillator (ICD) can sometimes demonstrate backup pacing spikes on electrocardiogram (ECG). Inappropriately timed pacing spikes on the ECG may reflect sensing and pacing issues due to underlying device or lead malfunction. Such a phenomenon may also be attributable to the presence of peculiar timing cycles or algorithms programmed in the device. We present an interesting case of low-voltage impedance measurement spikes from modern ICDs being confused with pacing spikes on telemetry system in a patient with recurrent ICD shocks. We report a case of a 63-year-old man with ischaemic cardiomyopathy and previous coronary artery bypass grafting who received a single-chamber ICD (Iforia VR-T DX ICD; Biotronik, Berlin, Germany) 2 years ago for secondary prevention of sudden cardiac death. The parameter settings were as follows: ventricle paced, ventricle sensed; pacing inhibited if beat sensed (VVI) mode, base rate 40 beats per minute (bpm); rate hysteresis and night rate: OFF; tachycardia detection: VT1/VT2/VF: 350/320/270 ms. Tachycardia therapies were programmed ON in all three tachycardia zones. He was admitted for syncope with ICD shocks and immediately placed on telemetry in the ward. Figure 1 shows the ECG telemetry recorded just before he received another ICD shock for polymorphic ventricular tachycardia (PMVT). His 12-lead ECG showed no ischaemic pattern, and his cardiac biomarkers were not elevated. He also did not have recent-onset angina or reduced effort tolerance. He was on optimal medical therapy for heart failure but not on any anti-arrhythmic agent.Figure 1: (Top) Telemetry tracing before implantable cardioverter defibrillator (ICD) shock during admission shows intermittent thoracic impedance (TI) spikes (red arrows) occurring (consistently at approximately 100 ms) following native QRS beat in the vulnerable period without effective capture. Vs–‘Vp’ (black interval) measured a rate of 50 bpm, which was above the lower pacing rate of 40 bpm, ruling out inappropriate pacing from ventricular undersensing and further confirming that these are TI spikes. An intrinsic ventricular premature beat (VPB) (*) and a captured ventricular paced beat (#) were also noted. (below) Telemetry tracing documenting polymorphic ventricular tachycardia (PMVT) leading to ICD shock during admission shows a short-long-short sequence, starting with a VPB (*) and ending with another VPB (*) occurring on the T wave of preceding sinus beat, initiating the R-on-T phenomenon and PMVT.Telemetry recordings showed noncaptured pacing spikes following QRS complexes on the ST-T segment [Figure 1]. An intrinsic ventricular premature beat (VPB) and a captured ventricular paced beat were also noted. At first glance of the telemetry recordings, one would suspect the pacing spikes following the QRS complexes to be a result of ventricular undersensing, which is often secondary to lead or device failure, insufficient voltage signal, device programming errors or electrolyte abnormalities.[1] Ventricular undersensing with inappropriate pacing in the vulnerable period of the ventricular repolarisation phase can lead to R-on-T phenomenon and PMVT in patients with cardiac implantable rhythm device.[2] ICD interrogation revealed normal sensing and pacing threshold values with a stable impedance trend. All rapid ventricular tachyarrhythmias were appropriately detected and successfully treated with the first shock. This gave reassurance that the ventricular tachycardia (VT)/ ventricular fibrillation (VF) signals were optimally sensed. Further electrogram (EGM) analysis revealed multiple sensed VPBs, initiating a short-long-short sequence, leading up to all the PMVT episodes. There was neither undersensing of native ventricular signals nor any evidence of inappropriately paced ventricular beats initiating the ventricular tachyarrhythmias on the EGM recordings. As device malfunction was definitively excluded as the cause of the ventricular arrhythmias, an invasive coronary angiogram was performed, which revealed a critical stenosis in the midportion of the saphenous venous graft adjoining the first obtuse marginal branch. This was successfully treated with a drug-eluting balloon. After revascularisation, there was no recurrence of short-coupling VPBs or ventricular tachyarrhythmias on the telemetry, and the patient did not experience any further ICD shock. No additional device intervention or programming change was required. The patient was discharged well. The pacing spikes in question were, in fact, thoracic impedance (TI) monitoring pulses delivered intermittently (1,024 data points each hour) by the device to detect pulmonary congestion. Measurement of TI is one of the heart failure diagnostic (programmable) features in modern Biotronik ICDs. Abnormal TI values correlate with early symptoms and signs of decompensated heart failure, allowing physicians to act early by titrating diuretic therapies. These test pulses deliver only small amounts of energy (1 [email protected] ms) and were destined to fall into the absolute refractory period, with a coupling interval of 100 ms after a sensed or paced right ventricle (RV) event. Thus, no capture could occur in the repolarisation phase of the action potential to incite any ventricular arrhythmias. As the TI measurement is dependent on subthreshold pacing pulses delivered in a unipolar fashion between the RV coil and the ICD, treating physicians who are familiar with this feature would instinctively understand why these spikes are readily recognisable on standard ECG and telemetry leads. The TI measurement feature in the Iforia series of ICDs, when programmed ON, would average the values collected each hour, which is then averaged again over a 24-h period to provide a daily TI value. Therefore, in a patient with a ventricular rate of 60 bpm, the unipolar spikes would be present on the ECG or telemetry up to 28% of the time (1,024 out of 3,600 cycles per hour), similar to previous reports of the Lumax ICD series.[3,4] These subthreshold test pulses would not be detected on the device storage counters or EGM recordings. In this patient’s telemetry tracings, the Vs–‘Vp’ interval consistently measured a rate of 50 bpm, which was above the lower pacing rate of 40 bpm, as seen in Figure 1, rendering the spikes unlikely to be inappropriate pacing from ventricular undersensing. Indeed, the intermittent noncaptured pacing spikes were consistently 100 ms from the native QRS complexes. With prior knowledge of this ICD programming feature, one would interpret these spikes as intermittent TI measurement delivery pulses, which coincide with the R-on-T ischaemic VPBs, rather than a result of ventricular sensing malfunction. A subsequent ICD interrogation would then further corroborate the findings of VPBs initiating episodes of PMVT noted on the telemetry. In conclusion, as more complex programmable options such as TI monitoring are added to modern ICDs, general hospitalists and cardiologists should strive to understand and recognise these features as the cause of seemingly abnormal ECG or telemetry recordings. This can prevent unnecessary investigations into device malfunctions, failure to prioritise critical interventions and potential harm to patient. Acknowledgement The authors would like to acknowledge Wendy Tan from Biotronik Singapore for her technical expertise. Financial support and sponsorship Nil. Conflicts of interest Chia PL is a member of the SMJ Editorial Board, and was thus not involved in the peer review and publication decisions of this article.

Twelve-lead electrocardiography (ECG) remains the gold standard for the diagnosis of cardiac arrhythmias. It provides a snapshot of the cardiac electrical activity while the leads are attached to the patient. As medical training is required to use the ECG machine, its use remains restricted to the clinic and hospital settings. These aspects limit the usefulness of 12-lead ECG in the diagnosis of cardiac arrhythmias, especially in individuals with short-lasting and infrequent paroxysmal symptoms. The introduction of ECG recording features in wearable and handheld smart devices has changed the paradigm of cardiac arrhythmia diagnosis, empowering patients to record their ECG as and when symptoms occur. This review describes contemporary ambulatory heart rhythm monitors commonly available in Singapore and their expanding role in the diagnosis of cardiac rhythm abnormalities.

Neoh, Eng Chuan Mphty1,; Chow, Jaclyn Jie Ling Mphty1; Hoon, Violet MBBS, MRCP2; Chow, Yvonne BSN, RN3; Lee, Seng Beo BSc4; Foo, David MBBS, MRCP2 Author Information

INTRODUCTION:Current delivery tools were not designed for left bundle branch area pacing (LBBAP). Challenges using these tools include lack of reach into the right ventricle and poor support for the lead to penetrate the interventricular septum. Concerns using stylet-driven leads (SDL) for LBBAP have been previously highlighted. Knowledge and the technical know-how of using SDL for LBBAP need to be evaluated in a fair and consistent manner. A stepwise approach is devised for use of Agilis HisProTM steerable catheter with Tendril STS Model 2088TC lead for LBBAP and evaluated for safety and reproducibility.METHODS:Consecutive patients undergoing LBBAP using the stepwise approach with Agilis HisProTM steerable catheter were analyzed. The safety, efficacy and reproducibility of the technique were evaluated. The lead parameters were analyzed in the immediate (1 day) and short-term period (3-6 months) post implantation.RESULTS:LBBAP was attempted in 41 patients using the stepwise approach of which 37 (90.7%) were successful. The lead parameters were stable in the immediate and short-term post implantation in all our patients. There was no significant difference between the group of patients with multiple repositioning of the lead compared to those successful at the 1st attempt. There were no acute or short-term lead and procedural complications.CONCLUSION:A stepwise and systematic approach using the Agilis HisProTM steerable catheter and proper handling of the Tendril STS Model 2088TC stylet-driven lead is an important part of the armamentarium to deliver LBBAP in a practical, effective and reproducible manner.

Background:Understanding the trajectories of metabolic risk factors for acute myocardial infarction (AMI) is necessary for healthcare policymaking. We estimated future projections of the incidence of metabolic diseases in a multi-ethnic population with AMI. Methods:The incidence and mortality contributed by metabolic risk factors in the population with AMI (diabetes mellitus [T2DM], hypertension, hyperlipidemia, overweight/obesity, active/previous smokers) were projected up to year 2050, using linear and Poisson regression models based on the Singapore Myocardial Infarction Registry from 2007 to 2018. Forecast analysis was stratified based on age, sex and ethnicity. Findings:From 2025 to 2050, the incidence of AMI is predicted to rise by 194.4% from 482 to 1418 per 100,000 population. The largest percentage increase in metabolic risk factors within the population with AMI is projected to be overweight/obesity (880.0% increase), followed by hypertension (248.7% increase), T2DM (215.7% increase), hyperlipidemia (205.0% increase), and active/previous smoking (164.8% increase). The number of AMI-related deaths is expected to increase by 294.7% in individuals with overweight/obesity, while mortality is predicted to decrease by 11.7% in hyperlipidemia, 29.9% in hypertension, 32.7% in T2DM and 49.6% in active/previous smokers, from 2025 to 2050. Compared with Chinese individuals, Indian and Malay individuals bear a disproportionate burden of overweight/obesity incidence and AMI-related mortality. Interpretation:The incidence of AMI is projected to continue rising in the coming decades. Overweight/obesity will emerge as fastest-growing metabolic risk factor and the leading risk factor for AMI-related mortality. Funding:This research was supported by the NUHS Seed Fund (NUHSRO/2022/058/RO5+6/Seed-Mar/03) and National Medical Research Council Research Training Fellowship (MOH-001131). The SMIR is a national, ministry-funded registry run by the National Registry of Diseases Office and funded by the Ministry of Health, Singapore.

Background The Singapore Cardiac Databank was designed to monitor the performance and outcomes of catheter ablation. We investigated the outcomes of paroxysmal supraventricular tachycardia (PSVT)-ablation in a prospective, nationwide, cohort study. Methods Atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular re-entry tachycardia (AVRT), or atrial tachycardia (AT)-ablations in Singapore from 2010 to 2018 were studied. Outcomes include acute success, periprocedural-complications, postoperative pacing requirement, arrhythmic recurrence and 1-year all-cause mortality. Results Among 2260 patients (mean age 45 +/- 18 years, 50% female, 57% AVNRT, 37% AVRT, 6% AT), overall acute success rates of PSVT-ablation was 98.4% and increased in order of AT, AVRT, and AVNRT (p < .001). Periprocedural cardiac tamponade occurred in two AVRT patients. A total of 15 pacemakers (6 within first 30-days, 9 after 30-days) were implanted (seven AV block, eight sinus node dysfunction [SND]), with the highest incidence of pacemaker implantation after AT-ablation (5% vs. 0.6% AVNRT vs. 0.1% AVRT, p < .001). Repeat ablations (0.9% AVNRT, 7% AVRT, 4% AT, p < .001) were performed in 78 (3.5%) patients and 13 (0.6%) patients died within a year of ablation. Among outcomes considered adjusting for age, sex, PSVT-type and procedure-time, AT was independently associated with 6-fold increased odds of total (adjusted odds ratio [AOR] 6.32, 95% confidence interval [CI] 1.95-20.53) and late (AOR 6.38, 95% CI 1.39-29.29) pacemaker implantation, while AVRT was associated with higher arrhythmic recurrence with repeat ablations (AOR 4.72, 95% CI 2.36-9.44) compared to AVNRT. Conclusions Contemporary PSVT ablation is safe with high acute success rates. Long-term outcomes differed by nature of the PSVT.

CLINICAL PRESENTATION A 24-year-old female suffered a sudden out-of-hospital cardiac arrest. Her colleagues performed cardiopulmonary resuscitation as she was noted to be pulseless. The paramedics arrived 30 minutes later and sinus rhythm was noted on the automated external defibrillator. The patient regained full consciousness upon arrival at the emergency department. Prior to her cardiac arrest, she experienced intermittent rapid palpitations over three days. She was a known case of ischaemic dilated cardiomyopathy, first diagnosed in her native country and subsequently on follow-up at another public healthcare institution in Singapore. Transthoracic echocardiography in 2018 revealed left ventricular ejection fraction (LVEF) 24%, severe left ventricular dilatation, regional wall motion abnormalities in multi-vessel territories, tenting of mitral valve with moderate mitral regurgitation, severe left atrial dilatation, normal right atrial size, normal right ventricular size and function. Cardiac magnetic resonance imaging in 2018 showed LVEF 12%, extensive transmural infarction with thinned out segments in the left anterior descending (LAD) coronary artery territory, left circumflex (LCX) territory and infarcted anterolateral papillary muscles. Coronary angiography in 2018 revealed 100% chronic total occlusion (CTO) in the proximal LAD with good collateral flow from the LCX and right coronary arteries (RCA), 90% stenosis in the proximal LCX, ectatic and aneurysmal dilatation of the proximal to mid RCA. Successful balloon angioplasty and stenting were then performed to the LCX stenosis. She was recommended to undergo the implantation of a subcutaneous implantable cardioverter-defibrillator for primary prevention of sudden cardiac arrest, but she declined. Serum lipid profile, complement 3, complement 4, homocysteine, anti-double stranded deoxyribonucleic acid, antinuclear, anti-phospholipid, anti-Smith, anti-Ro, anti-La, anti-ribonucleoprotein, anti-scleroderma 70 and anti-Jo-1 antibodies were all negative. There was a possibility of her having suffered from Kawasaki disease during her childhood, but the hospital records then were not available. Her father had experienced sudden cardiac arrest in her native country at age of 40 and she was told it was likely due to an acute myocardial infarction. Following admission, the patient was hemodynamically stable. Serum troponin I level rose from 18 to 435 ng/mL. No significant serum electrolyte abnormality was detected. Figures 1 and 2 show her serial 12-lead electrocardiograms (ECG). What do these two ECGs show?Figure 1: 12-lead electrocardiogram on admission.Figure 2: 12-lead electrocardiogram 8 hours post admission.ECG INTERPRETATION Figure 1 shows sinus rhythm with right bundle branch block (RBBB) as evidenced by the following features: QRS duration >120 ms; RSR' pattern in leads V1 and V2 and S wave in leads I, aVL, V5 and V6. It also shows left anterior fascicular block as demonstrated by the following: left axis deviation; qR complexes in leads I, aVL and rS complexes in leads II, III and aVF. The PR interval was top normal at 200 ms. Figure 2 shows sinus rhythm with left bundle branch block (LBBB): QRS duration >120 ms; dominant S wave in lead V1; absence of Q wave in leads I, V5 and V6 and monomorphic R wave in leads 1, V5 and V6. The PR interval was top normal at 200 ms. These two ECGs revealed that the patient had alternating bundle branch block, with Figure 2 ECG being her baseline. CLINICAL COURSE Computed tomography brain scan was performed and did not show any mass effect, acute intracranial haemorrhage, established territorial infarct or changes of established hypoxic ischaemic encephalopathy. Transthoracic echocardiography revealed LVEF 20%. Coronary angiography showed the known LAD artery CTO with good collateral flow from the LCX and RCA, ectatic proximal RCA with mid segment aneurysm and a patent LCX stent. Guidelines directed medical therapy was instituted. A transvenous single chamber implantable cardioverter-defibrillator (ICD) was implanted to prevent against sudden cardiac death from ventricular tachyarrhythmias. DISCUSSION Alternating bundle branch block refers to the occurrence of RBBB and LBBB in the same patient at different times. This phenomenon denotes likely severe disease in the infra-Hisian conduction system involving both bundle branches, with a propensity for developing complete atrioventricular (AV) block. The likelihood of complete AV block is higher in those who develop alternating bundle branch block at almost the same heart rates and with PR interval changes.[1] In our patient, the bundle branch block morphology changes occurred at 90–95 beats per minute but the PR interval remained top normal at 200 ms in both ECGs. The possible causes of cardiac arrest in this patient included acute coronary syndromes, ventricular tachyarrhythmias and infra-Hisian conduction system disease leading to AV blocks or ventricular standstill. Coronary angiography did not reveal any need for further coronary revascularisation. ICD implantation was definitely indicated in view of her persistently poor LVEF since 2018, despite being compliant to guidelines directed medical therapy, and having survived an out-of-hospital cardiac arrest. The alternating bundle branch block was a crucial determinant of the final type of ICD implanted for this patient to prevent sudden cardiac arrest from ventricular tachyarrhythmias. Given her very young age and active lifestyle, a subcutaneous ICD can be considered.[2] However, the presence of alternating bundle branch block implied a high risk of progression to complete AV block necessitating cardiac pacing which the subcutaneous ICD was incapable of and hence a transvenous ICD system would be indicated. Although a VDD lead ICD system can be considered, given the patient's petite body habitus, the long length of the VDD ICD lead may make lead positioning suboptimal. In view of the possible anticipated high-ventricular pacing burden, a biventricular ICD system was recommended to the patient.[3] She was also offered alternative options of a single or dual chamber ICD with a view to upgrade to a biventricular system in the future should she develop pacing dependence. Given her non-resident status, cost consideration was important and that led the patient to eventually choose a single chamber ICD system. CONCLUSION Alternating bundle branch block may be a subtle finding but carries huge clinical implications. It should be actively monitored in patients with underlying structural and coronary heart diseases. Financial support and sponsorship Nil. Conflicts of interest Chia PL is a member of the SMJ Editorial Board, and was thus not involved in the peer review and publication decisions of this article. SMC CATEGORY 3B CME PROGRAMME Online Quiz: https://www.sma.org.sg/cme-programme Deadline for submission: 6 pm, 30 December 2022