Abstract Background/Introduction Atrial fibrillation (AF) and heart failure with reduced ejection fraction (HFrEF) frequently coexist and confer a high thromboembolic risk. Guidelines recommend ≥3 weeks of oral anticoagulation before electrical cardioversion (ECV), but the residual risk of left atrial (LA) thrombus or dense spontaneous echo contrast (SEC) in this high-risk population is uncertain. Purpose To determine the prevalence and predictors of LA thrombus or dense SEC in patients with HFrEF undergoing elective ECV for persistent AF or flutter despite guideline-recommended anticoagulation, and to explore their clinical implications. Methods Single-centre retrospective cohort of patients with HFrEF (LVEF ≤40%) scheduled for elective ECV for persistent AF/flutter. All received oral anticoagulation for ≥3 weeks (vitamin K antagonists with INR ≥2.0, or direct oral anticoagulants at label-conforming doses). All underwent pre-ECV transoesophageal echocardiography to detect LA thrombus or dense SEC (grade 3–4). Clinical, echocardiographic and laboratory variables (including NT-proBNP) were compared between patients with and without thrombus/SEC. Independent predictors were assessed by multivariable logistic regression. Clinical outcomes were evaluated during follow-up. Results Seventy-nine patients were included (median age 66 years, 73% male); 87% had AF and 13% flutter. Direct oral anticoagulants were used in 67% and vitamin K antagonists in 33%. LA thrombus or dense SEC was found in 19 patients (24.1%) despite guideline-recommended anticoagulation. Compared with patients without thrombus/SEC, these patients had higher NT-proBNP levels (median 7260 vs 2715 pg/mL, p=0.009), more frequent implantable cardioverter-defibrillator (37% vs 10%, p=0.017) and right atrial dilatation (73% vs 41%, p=0.04), with no differences in age, comorbidities, CHA2DS2-VA score or type of anticoagulant. In multivariable analysis, NT-proBNP >6500 pg/mL independently predicted thrombus/SEC (OR 78.6; 95% CI 1.4–4266; p=0.032). Among 12 patients with initial thrombus/SEC who underwent repeat transoesophageal echocardiography, resolution was documented in 10 (83.3%) after tailored anticoagulation strategies. Over a median follow-up of 15 months (IQR 8–36), baseline thrombus/SEC was associated with higher all-cause mortality (HR 6.0; 95% CI 1.3–26.7; p=0.02) and cardiovascular mortality (HR 6.3; 95% CI 1.1–38.0; p=0.04). Conclusions In patients with persistent AF/flutter and HFrEF, nearly one in four have LA thrombus or dense SEC at pre-ECV imaging despite guideline-recommended anticoagulation, questioning the safety of the standard strategy in this high-risk group. Elevated NT-proBNP identifies patients at particularly high risk. These findings support systematic pre-procedural imaging to rule out LA thrombus in patients with AF and systolic heart failure undergoing elective ECV.

Cryoballoon ablation (CA) procedures require optimal occlusion of the pulmonary veins (PV), which is conventionally evaluated by contrast injection through the catheter tip. This technique has some weaknesses such as risk of allergic reactions, nephrotoxicity, requirement of a second operator, among others. PV pressure waveform analysis is an alternative method for confirming occlusion, however, multicentre assessment of periprocedural efficacy and safety is lacking. To describe the intra-procedural performance, safety and long-term results of routine pressure-based CA. In this independent prospective multicentre and multi-brand observational study, baseline, procedural and follow-up data from consecutive pressure-guided cryoballoon ablations were collected. Pressure waveforms were classified into type 1 (presence of "a-wave" and/or symmetric "v-wave", meaning incomplete PV occlusion) and type 2 (absence of "a-wave" and asymmetric "v-wave", meaning complete PV occlusion). A total of 235 patients (mean age: 61 ± 10 y.) with paroxysmal (57.8%) or persistent AF (42.2%) from 9 centres were enrolled. Complete PV isolation was achieved in 226 patients (97%). The operators switched to contrast in 16 cases (6.8%). Thirteen non-serious (5.5%) and 0 serious procedure-related adverse events were reported. AF/AT-free survival rate after the index procedure was 60.3% after a median follow-up of 359 days. Ten patients (4.3%) required a second procedure. Routine PV cryoablation guided exclusively by pressure waveforms was safe and could be achieved in most of the patients. No contrast requirement and a high single shot isolation rate (78%) were important advantages of this approach. Long-term clinical efficacy was equivalent to that reported with the conventional approach.Pressure waveforms classification Catheters,procedural & clinical outcomes

Abstract Funding Acknowledgements None. Introduction Bezold-Jarisch is a cardioinhibitory reflex originating in cardiac vagal receptors, more concentrated in the inferoposterior wall of left ventricle, whose stimulation produces bradycardia and hypotension. The limited evidence suggests that vagal tone would predominate in younger individuals, whereas sympathetic tone would predominate in the elderly, resulting in a more striking Bezold-Jarisch reflex response among younger patients. Its maximum expression would be the occurrence of acute complete atrioventricular block (cAVB). Methods Observational, retrospective, single-centre analysis of consecutive patients hospitalised in the CCCU for STEACS with RCA or ADA as culprit artery (CA) between July 2011 and September 2022. We analysed the influence of age on the incidence of acute cAVB. Linear trend analysis and multivariate analysis were performed. Results A total of 723 patients with RCA as CA were included, with the baseline characteristics listed in Table1. Patients were divided into 4 groups: under 60 years (n=316 43.7%), 60-69 (n=223 30.8%), 70-79 (n=122 16.9%) and 80 or older (n=62 8.6%). The incidence of acute cAVB was 10.4%, 14.3%, 16.4% and 25.8% respectively (Fig1). A Cochran-Armitage analysis was performed, showing a significant linear trend between age and the incidence of acute cAVB (p=0.001). A multivariate analysis was performed using stepwise regression including age, sex, diabetes, hypertension, obesity, peripheral arterial disease, systolic blood pressure (SBP) at admission, renal failure, COPD, Killip-Kimbal (KK) score at admission and treatment with ticagrelor (for its described adenosine-like effect). Age (p=0.011), KK score (p<0.001) and lower SBP (p<0.001) were associated with a higher incidence of acute cAVB. Regarding the need for transient pacemaker, 6.2% of patients under 60, 7.7% aged 60-69, 10.1% aged 70-79, and 22.0% aged 80 and over required its implantation. As with cAVB, there was a significant linear trend between age and device implantation (p<0.001). Permanent pacemaker was implanted in only 6 patients. In-hospital mortality was significantly higher in patients with acute cAVB than all other patients with RCA infarction (7.9% vs 2.1%; p=0.001). Finally, as controls, acute cAVB data were analysed in patients with STEACS with ADA as CA (N=837). 366 patients (43.7%) were under 60 years, 204 (24.4%) 60-69, 155 (18.5%) 70-79 and 112 (13.4%) 80 or older. Only 10 patients presented with cAVB (1.2%), with no differences between those younger and older than 75 years (1.0% vs 2.3% respectively; p=0.13). Given the low incidence of cAVB in this group no further analysis was performed. Conclusion In RCA STEACS patients, there is a significant trend towards a higher incidence of acute cAVB with increasing age. These data suggest that older patients do not have a mitigated response to Bezold-Jarisch reflex. The inverse relationship between SBP and occurrence of cAVB supports the reflex nature of the mechanism.Table 1.Baseline characteristics.Fig 1.cAVB incidence among age groups.

Abstract Background Cryoballoon ablation (CA) procedures require optimal occlusion of the pulmonary veins (PV), which is conventionally evaluated by iodine contrast injection through the catheter tip. This technique has some weaknesses such as risk of allergic reactions, nephrotoxicity, requirement of fluoroscopy (sometimes at high doses), requirement of a second operator, among others. PV pressure waveform assessment is an alternative method for confirming occlusion, however, multicentre assessment of periprocedural efficacy and safety is lacking. Purpose To describe the intra-procedural performance and safety of routine pressure-based CA. Methods In this independent prospective multicentre observational study, baseline and procedure data from consecutive pressure-guided CB ablations were collected. Operators were not required to have experience in pressure-guided CA for participating in the registry. They were asked to classify the pressure waveform curves into type 1 (presence of "a-wave" and/or symmetric "v-wave", meaning incomplete PV occlusion) and type 2 (absence of "a-wave" and asymmetric "v-wave", meaning complete PV occlusion), Figure 1. The primary endpoint was PV isolation in all veins without use of contrast. Procedure performance and adverse events were also analyzed. Results A total of 150 patients (mean age: 61 ± 10 y.) with paroxysmal (62%) or persistent AF (38%) were included and underwent pressure-guided CA in 9 centres from Spain. Complete PV isolation was achieved in 148 patients (98%). The operators switched to contrast use in 14 cases (9%), mainly to double check the occlusion. Total procedure and fluoroscopy time were 97 ± 39 and 19 ± 10 min respectively. There were 7 (4.7%) procedure related adverse events: 4 phrenic nerve palsy (3 of them were transient), 1 transient coronary ST elevation (before ablation), 1 gastroparesis and 1 femoral pseudoaneurysm. Most relevant results are summarized in Figure 2. Conclusion In this multicentre and multi-brand assessment, CA guided by pressure waveforms provided outstanding procedural outcomes, which were equivalent to those reported with the conventional approach. All operators could easily obtain and identify the waveform without a specific learning curve, avoiding the use of iodine contrast in most cases. The long-term efficacy of this approach will be presented in future analyses.Pressure waveforms types in cryoablationProcedural data

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Acute coronary syndrome (ACS) is one of the most common health problems in the world, and the leading cause of death. The goals of this study are to determine ACS incidence and the seasonal distribution of ocurrence (Spring/Summer/Autumn/Winter) as well as clinical outcomes per season. Methods Retrospective and observational analysis of consecutive patients hospitalized for ST-elevation myocardial infarction (STEMI) in the Critical Coronary Care Unit (CCCU) of a tertiary center with Mediterranean climate from July 2011 to September 2022. We analyzed the influence of the seasons on the incidence and characteristics of ACS. Results We enrolled a total of 1668 patients: 431 in Winter, 382 in Spring, 405 in Summer and 450 in Autumn, with the baseline characteristics summarized in Table 1. There were no differences in baseline characteristics among the 4 seasons, except for the higher prevalence of obesity in Autumn. There was no statistically significant difference in the incidence of STEMI among seasons, although numerically the highest incidence was recorded in Autumn. The occurrence of ACS was not different according to age or sex. ACS complications were not statistically different among seasons with similar incidence of ventricular arrythmias (VT, VF), invasive mechanical ventilation support, need for inotrope/vasopressor support or development of de-novo atrial fibrillation. In-hospital mortality is less frequent in Autumn, but the differences did not reach statistical significance. Conclusions In this Mediterranean climate cohort, STEMI incidence was higher in Autumn, although no differences in clinical profile or outcomes were found among seasons.

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The incidence of ventricular tachycardia (VT) and ventricular fibrillation (VF) in the acute phase of infarction (first 24-48 hours) has declined over recent decades, probably due to the uptake of reperfusion strategies and the early use of beta-blockers. However, according to some series, 6–8% of patients still develop hemodynamically significant VT or VF during this phase. Purpose The objective of our study was to evaluate the baseline characteristics of patients who suffered VT or VF in the acute phase of the infarction and to create a predictive model of ventricular arrhythmias in this setting which allow us to anticipate arrhythmic events. Methods We performed an observational, retrospective, and single-centre study carried out through the review of clinical records of patients who suffered an acute myocardial infarction with ST-segment elevation (STEMI) and were admitted in our Coronary Care Unit between July 2011 and August 2022. Results In our cohort we observed 179 episodes of VT/VF (10,7%) in a population of 1668 patients underwent STEMI. The mean age in this subgroup was 61,69±12,61 years old, 78% were males and 56% smokers. Approximately a quarter of the patients were diabetic or obese. There was a very low percentage of previous myocardial infarction (12%) and heart failure (3%) (Table 1). We estimated the best prediction model (Mallows’ Cp=5.12) for VT/VF. The variables included in our model (LL=-435,43) were: male sex, absence of diabetes, smoking habit, use of fibrinolysis, worst Killip at admission and hypotension at admission (Table 2). Conclusion The presence of VT or VF in the acute phase of infarction is still considered a controversial factor in the prognosis of these patients. In our cohort we identified that males, smokers, non-diabetics, and the use of fibrinolysis and the worst haemodynamical situation at admission were independent predictors of developing VT/VF in this context.

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Atrial fibrillation (AF) and ischemic cardiomyopathy share common risk factors. The aim of the study was to analyse clinical profile and mortality of patients presenting new-diagnosed AF in the context of acute coronary syndrome (ACS). Methods Retrospective, observational study of patients presenting with ACS in Acute Coronary Care Unit (ACCU) between 2011-2022. Baseline, demographic characteristics and clinical outcomes were studied. Results 3161 patients with ACS were admitted to the ACCU during this period, of whom 5.1% presented de-novo AF. The remaining percentage were patients without AF (86.8%) or with previously known AF (8.1%). 73.7% were male and 52.8% of the ACS presented with ST elevation. Baseline characteristics in both groups are shown in Table 1. Most frequent culprit vessel was the anterior descending artery in both groups, followed by right coronary artery. Severe bleeding was significantly more frequent in patients with de-novo AF (25.4% vs 9%, p<0.01). On univariate analysis, in-hospital all-cause mortality was significantly higher in the de-novo AF group (17.3% vs 5.8%, p<0.01), as well as in patients with previously known AF (10.9% p<0.01), compared to those without AF. In the multivariate analysis of all-cause mortality (Table 2) after adjusting for baseline characteristics, de-novo AF did not reach statistical significance. Conclusion De-novo AF is a relatively uncommon complication in ACS, identifying a high-risk profile patient with higher in-hospital mortality.

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Tachycardiomyopathy is a common cause of reversible left ventricular disfunction, whose predictors are not well-stablished. Its individual estimation would be useful for the decision-making process. Methods Retrospective single-centre, observational study of consecutive patients with diagnosed tachycardiomyopathy between September 2014-2020. Sample was split in 2 parts: first for the construction of the lineal-regression model selected by the all-possible equation’s method (sample 1, 70% of the cohort), second for its validation (sample 2, 30%). Results 113 patients were gathered in this period. Most prevalent arrhythmia was atrial fibrillation (75.2%), followed by atrial flutter (22.1%), ventricular extrasystole (5.3%) and atrial tachycardia (2.65%). Mean left ventricular ejection fraction (LVEF) at diagnosis was 33.7% (±6.48) and mean left ventricular end-diastolic diameter 56.3 mm (±6.97). Rhythm control was achieved in 81.4% of patients, of whom 79.3% underwent an ablation procedure. After a mean of 11.4 months, mean final LVEF was 55.1% (±6.04). Recovered LVEF (final minus initial) was calculated in all patients. Using sample 1 131,071 models were calculated. The best model was selected based on the Mallows index (Picture 1), composed by arterial hypertension, sleep apnea syndrome, atrial fibrillation as the culprit arrythmia, LVEF at diagnosis and rhythm control strategy. The selected model explained nearly half of the individual variability of LVEF (R2 0.476). Subsequently in sample 2, predicted recovered LVEF was compared with the observed one (Picture 2), without significative differences in the determination coefficient r2 (R2 - r2 = -0.0064). Conclusion Arterial hypertension, sleep apnea syndrome, atrial fibrillation as the culprit arrythmia, LVEF at diagnosis and rhythm control strategy predicted LVEF recovery in tachycardiomyopathy patients.

Abstract Introduction Arrhythmia-Induced Cardiomyopathy (AIC) is a cardiac disfunction secondary to fast, asynchronous or irregular ventricular contraction. Its diagnosis is usually retrospective, subsequently of the recovery of the left ventricle ejection fraction (LVEF) after controlling the responsible arrythmia (most frequently atrial fibrillation (AF)). Objective Our aim is to try to estimate the recovering of LVEF in patients diagnosed of AIC caused by AF, based on individual baseline characteristics. Methods Retrospective analysis of patients diagnosed with AIC related to AF between January 2015–2022. Clinical and demographic characteristics, as well as echocardiographic parameters prior to diagnosis and after recovery of ventricular function, were assessed. Recovered LVEF (final minus initial LVEF) was calculated in all patients. The best model was selected from the method of all possible equations, the one with the lowest Mallows Cp index, maintaining a sufficiently high multiple correlation coefficient (R2). Results 134 patients with AIC were gathered in this period, 99 of them AF-related. Baseline characteristics are summarized in Image 1. The changes in the values of LVEF, left ventricle end-diastolic diameter and (LVEDD), tricuspid annular plane systolic excursion (TAPSE), which represents both left and right ventricular ejection fraction are showed in Image 2. The LVEF recoveredwith treatment was 22±8,5%. The model was selected using up to 16 potential variables: age, sex, chronic kidney disease (CKD), obesity, enolism, hypertension, diabetes, obstructive sleeping apnoea (OSA), LVEF at the diagnosis, heart rate at diagnosis, angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARBs), neprilysin inhibitors (ARNI), mineralocorticoid receptor antagonists (MRA), ablation performed, rhythm control strategy and the interaction between ablation andrhythm control (the latter being rejected because of collinearity). 32.767 models were estimated. The best model was: Recovered LVEF = 51.79 + 1.15×Female Sex − 1.11×OSA − 4.40×RNI − 091×LVEF at diagnosis + 3.43×Rhythm control. The Cp of the selected model was 2.07 and R2 0.496, which means that 49.6% of individual variability of recovered LVEF was justified by this simple model. After that, we performed an internal control using cross-validation, which did not show significative differences according to the estimation ability of the model (0.496 − 0.474 = 0.022, <10%). Conclusion Female sex, absence of OSA, the lower the LVEF at the diagnosis, the absence of treatment with ARNI and the rhythm control as the treatment strategy predicted higher LEVF recovery in patients with AIC caused by AF, explaining nearly half to the individual variability. Funding Acknowledgement Type of funding sources: None.

Abstract Introduction Tachycardiomyopathy is a common cause of left ventricular systolic dysfunction (LVSD), whose complete resolution after arrhythmia control is highly variable among patients. Purpose To assess the associated factors with complete left ventricular reverse remodeling (CLVRR) in patients with confirmed tachycardiomyopathy. Methods Retrospective single-centre, observational study of consecutive patients with diagnosed tachycardiomyopathy between January 2015–2022. CLVRR was defined by a recovered left ventricular ejection fraction (RLVEF) >55% and a left ventricular end-dyastolic diameter (LVEDD) <55 mm assessed by transthoracic echocardiography. Results 134 patients were gathered in this period. Patients with previous known LVSD or LV dilatation were excluded from the analysis (n=6). Baseline characteristics are displayed in Image 1. Most frequent arrhythmia was atrial fibrillation (73.8%), followed by atrial flutter (25.4%), atrial tachycardia (2.2%) and ventricular extrasystole (5.2%). 99.2% of patients were treated with beta-blockers, 71.6% with ACEI/ARBs, 23.9% with neprilysin inhibitors and 64.2 with aldosterone receptor antagonist. Rhythm control was achieved in 82.1% of patients, of whom 80% underwent an ablation procedure after a mean of 8.2 months. After 10.8 months since LVSD, mean RLVEF was 55.4% (+6.3) and mean LVEDD 52.1 mm (+5.8). CLVRR was observed in 50% of patients. A multivariate analysis was performed in a stepwise fashion to assess associated factors, including baseline information (medical history, echocardiographic information and received treatment, both pharmacological and ablation). CLVRR was associated with female-sex (coefficient 1.18; p=0.009) and severe baseline left ventricular disfunction (coefficient −0.80; p=0.041), corrected by previous alcohol abuse history (coefficient 0.94; p=0.055) and a rhythm-control strategy (coefficient 0.98; p=0.052) which didn't reach complete statistical significance. Conclusion Women, patients without severe LV dysfunction at baseline, with history of previous alcohol abuse and receiving a rhythm-control strategy were associated with a complete left ventricular reverse remodeling in patients with tachycardiomyopathy. Funding Acknowledgement Type of funding sources: None.

Abstract Background The development of heart failure (HF) is a factor of poor prognosis in patients admitted due to acute coronary syndrome (ACS). Research question The aim of this study is to establish the usefulness of lung ultrasound (LU) to predict patients at risk of developing HF and the need for mechanical ventilation. Methods Prospective study with consecutive inclusion of patients with ACS type infarction without HF on admission and admitted to our centre between February 2017 and 2018. A lung ultrasound was performed in the first 24 hours, considering it positive when they presented 3 or more B lines in two or more quadrants of bilateral form. The result was related to the need for mechanical ventilation. Results We included 119 patients (65.1±12.8 years, 75.6% men), 12.6% presented a need for mechanical ventilation. Patients with a positive LU adjusted for a history of atrial fibrillation and the Killip-Kimball class have a risk 72.79 [95% CI: (9.21, 575.28)] times higher than needing mechanical ventilation at any time of the follow-up Adjusted for sex and heart rate, the result is 101.28 [95% CI: (12.83, 799.15); p=0.00005] times more risk of needing mechanical ventilation at any time of follow-up. Conclusions LU has a high positive predictive value for the development of severe HF and the need for mechanical ventilation, in patients admitted for ACS. Our findings suggest that LU should be incorporated in the initial stratification of patients with ACS. Survival analysis mechanical ventilation Funding Acknowledgement Type of funding source: None