BACKGROUND:Recent animal models show that frequent premature atrial complexes (PACs) induce atrial remodeling through conduction slowing without altering the atrial effective refractory period (AERP), suggesting a mechanism distinct from atrial fibrillation (AF)-induced remodeling. However, the impact of frequent PACs on human AERP remains unclear. OBJECTIVES:The purpose of this study was to compare AERP characteristics in patients with isolated frequent PACs and those with AF. METHODS:This prospective study included patients undergoing ablation for isolated frequent PACs, paroxysmal atrial fibrillation (PAF), or persistent AF. After a 6-beat 600-ms drive train (S1), the S2 interval was increased in 10-ms steps until atrial capture occurred; the longest noncapturing S2 was defined as AERP. AERPs were measured at 9 sites, including 4 pulmonary veins (PVs), and 5 extra-PV regions. Interatrial conduction time was measured from P-wave onset to latest activation on the coronary sinus catheter. RESULTS:A total of 143 patients were included (PAC: n = 21, burden 36 ± 17%; PAF: n = 65; persistent AF: n = 57). In the PVs, AERP was longest in PAC, intermediate in PAF, and shortest in persistent AF (PAC: 254.9 ± 22.4 vs PAF: 229.5 ± 38.6 vs persistent AF: 205.4 ± 29.1 ms; P < 0.001). In extra-PV regions, AERPs were similar between PAC and PAF, whereas persistent AF showed significantly shorter values (256.0 ± 21.7 vs 260.9 ± 28.2 vs 225.7 ± 24.2ms; P < 0.001). Interatrial conduction time was comparable between PAC and PAF but prolonged in persistent AF (122 ± 12 vs 118 ± 20 vs 131 ± 23 ms; P = 0.004). Multivariable regression demonstrated arrhythmia type as an independent determinant of both PV and extra-PV AERP (standardized β = -0.54 and -0.62, respectively; P < 0.001). Within PAC patients, AERPs did not differ by PAC origin. CONCLUSIONS:Isolated frequent PACs were characterized by preserved AERP in both PV and extra-PV regions. Shorter AERPs in the PVs in PAF and more widespread AERP shortening in persistent AF may reflect the transition from PACs to PAF and then progression to persistent AF.

BACKGROUND:Our previous ex-vivo study showed that shorter inter-lesion time (ILT), defined as the interval between consecutive ablations, enhances lesion depth and may reduce residual conduction during linear ablation. Its impact under practical scenarios, such as parallel catheter orientation and shorter inter-lesion distance (ILD), remains unclear. To investigate how ILT, catheter orientation, and ILD affect lesion depth during linear ablation using high-power (HP) and very-high-power short-duration (vHPSD) settings in an ex-vivo model. METHODS:Linear lesions (six per line) were created using the QDOT MICRO catheter (Biosense Webster). Phase 1 evaluated catheter orientation (parallel vs. perpendicular), and Phase 2 compared ILDs (6 mm vs. 4 mm). Minimum perpendicular inter-lesion depths and maximum lesion depths were measured under short ILT (15 s) or long ILT (60 s) using vHPSD (90 W/4 s) or HP (50 W, Ablation Index 350). RESULTS:Short ILT consistently increased maximum and inter-lesion depths across all settings. In Phase 1, parallel orientation produced deeper lesions than perpendicular under HP, whereas under vHPSD, parallel orientation generated shallower lesions. In Phase 2, lesions at ILD 4 mm were deeper than at 6 mm for the same ILT. Notably, short ILT at ILD6 mm achieved inter-lesion depths comparable to long ILT at ILD4 mm, suggesting an additive benefit of ILT shortening, though it cannot replace a short ILD. CONCLUSION:In this proof of concept study, shorter ILTs enhanced lesion depth across all conditions. The effect of catheter orientation varied between HP and vHPSD, suggesting that the optimal strategy to maximize ILT effectiveness depends on ablation setting.

Background Cardiac metastasis from tongue squamous cell carcinoma (TSCC) is extremely rare. Endocardial involvement, particularly in the left heart, occurs in only 3%-6% of cases and is often asymptomatic until advanced stages. Early detection is challenging but critical to prevent life-threatening complications.Case summary A 75-year-old man with a history of TSCC presented with non-sustained ventricular tachycardia (NSVT) detected during routine post-operative surveillance. Transthoracic and transoesophageal echocardiography, cardiac magnetic resonance imaging, and contrast-enhanced computed tomography revealed a well-defined mass in the left ventricular cavity infiltrating the anterolateral papillary muscle. Surgical excision with concomitant mitral valve replacement was performed. Histopathology confirmed metastatic TSCC. Post-operatively, ventricular arrhythmias resolved completely, and the patient remained recurrence-free with preserved cardiac function during follow-up.Discussion This case highlights the rare presentation of left-sided endocardial cardiac metastasis from TSCC manifesting as potentially life-threatening ventricular arrhythmias. It emphasizes the importance of considering cardiac metastasis in cancer patients with new-onset arrhythmias, demonstrates the diagnostic utility of multi-modal imaging, and underscores the therapeutic benefit of timely surgical intervention in selected patients.

Background The left bundle branch has traditionally been described as consisting of anterior and posterior fascicles, but increasing attention has focused on a third component, the left septal fascicle. Electrocardiographic (ECG) findings consistent with left septal fascicular block (LSFB) have been described; however, their clinical significance in acute coronary syndrome (ACS) remains uncertain. Objective This study aimed to characterize the clinical presentation associated with a transient LSFB-like ECG pattern in patients with ACS undergoing emergency percutaneous coronary intervention (PCI). Methods Among 789 consecutive patients with ACS treated with emergent PCI between 2017 and 2024, we identified patients with a transient LSFB-like ECG pattern, defined by a marked increase in anterior QRS forces (R-wave amplitude ≥15 mm in lead V2) during the acute ischemic phase with attenuation after revascularization. Patients with other causes of prominent anterior QRS forces were excluded. Clinical, angiographic, and outcome data were retrospectively analyzed. Results A transient LSFB-like ECG pattern was identified in 8 patients (1.0%), resolving after reperfusion in all cases. All culprit lesions were located in the proximal left anterior descending artery (LAD) at or proximal to the first septal branch. Ventricular fibrillation occurred in 3 patients (37.5%) before PCI. No recurrence of the LSFB-like pattern was observed on follow-up ECG. Conclusion A transient LSFB-like ECG pattern was uncommon but associated with proximal LAD involvement in this ACS cohort. Recognition of this dynamic ECG pattern may help identify septal ischemia and proximal LAD lesions. Further studies are warranted to refine ECG definitions and to clarify the clinical implications of LSFB-like patterns.

BACKGROUND:Cardiac sarcoidosis (CS) is a granulomatous disease that can lead to heart failure and fatal arrhythmias. While 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is useful in assessing active inflammation, its role in guiding immunosuppressive therapy and predicting long-term prognosis remains unclear. METHODS:This retrospective study analyzed 36 CS patients who underwent FDG-PET-guided immunosuppressive therapy between 2012 and 2017. FDG uptake was quantitatively evaluated before treatment, at 6 and 12 months, and annually thereafter. Prognostic outcomes, including major adverse cardiac events (MACE) and mortality, were assessed. RESULTS:Over a median follow-up of 8.2 years, 11 patients experienced MACE, and 7 died. SUVmax at 6 months (six-M SUVmax) and 1 year (one-y SUVmax) significantly correlated with prognosis. Patients with one-y SUVmax >4.5 had a higher risk of adverse events (p < 0.0001), while patients with six-M SUVmax >3.5 had a higher risk of adverse events (p = 0.035). Lower left ventricular ejection fraction (LVEF <40 %) was also associated with worse outcomes. Those requiring a final prednisolone (PSL) dose ≥10 mg had increased mortality (p < 0.0001). CONCLUSION:FDG-PET-derived SUVmax at 1 year is a critical prognostic indicator in CS patients undergoing immunosuppressive therapy. Poor response to PSL, indicated by persistent FDG uptake, correlates with worse outcomes. Regular FDG-PET monitoring and personalized treatment strategies are essential to optimizing long-term management.

18F-Fludeoxyglucose (FDG) PET/CT is an effective tool for detecting active cardiac sarcoidosis (CS), but often has difficulty distinguishing CS lesions from physiological myocardial accumulation. We investigated the potential of the glucose metabolic rate (MRglc, mg/min/100mL) from four-dimensional FDG PET/CT in distinguishing between CS and physiological accumulation. Additionally, we compared CS delineation between MRglc and standardized uptake value (SUV). A total of 192 individuals with CS or suspected CS who underwent four-dimensional FDG PET/CT after 18 h fasting was enrolled. Ultimately, 45 individuals with CS and 14 patients with physiological accumulation, with SUVmean ≥ 2.7 accumulation in the left ventricular myocardium, were analyzed. The SUV, MRglc, and the ratio of MRglc to SUV (MRglc/SUV) were calculated for each lesion with SUVmean ≥ 2.7 using data acquired between 30 and 50 min on four-dimensional FDG PET/CT. In the CS group, lesion-to-normal myocardium contrast ratios on MRglc and SUV images were compared. A total of 127 lesions from 45 individuals with CS and 43 physiological accumulations from 14 individuals were analyzed. The SUV, MRglc, and MRglc/SUV for CS lesions were significantly lower than those for physiological accumulations (SUV, 4.26±1.35 vs. 6.06±3.28; MRglc, 1.91 ± 1.02 vs. 3.78 ± 2.11; MRglc/SUV, 0.43 ± 0.14 vs. 0.63 ± 0.14; p < 0.0001). Receiver operating characteristic analysis revealed that the ability to discriminate CS lesions from physiological accumulations yielded areas under the curves of 0.656, 0.808, and 0.849; sensitivities of 68, 76, and 73

BACKGROUND:Heart failure (HF) patients who exhibit improvement in systolic function following atrial fibrillation (AF) ablation may experience better outcomes than those who do not. However, the prognostic significance of such improvement compared to originally preserved systolic function remains unclear. METHODS:Among 1538 patients undergoing AF ablation, those meeting HF criteria were included. Patients with systolic dysfunction (n = 272) and those with a high likelihood of HF with preserved ejection fraction (HFA-PEFF score ≥ 5; pEF group, n = 293) were analyzed. The former were further subdivided based on post-procedural left ventricular ejection fraction (LVEF) into improved EF (imp-EF, LVEF ≥50 %) and non-improved EF (non-imp-EF, LVEF <50 %) groups. The primary endpoint was a composite of all-cause mortality and HF hospitalization, comparing the imp-EF and pEF groups. RESULTS:Among 272 patients with systolic dysfunction, 127 were categorized as imp-EF. After propensity-score matching (101 per group), the imp-EF group had comparable risk of the primary endpoint as the pEF group [HR 0.40 (0.13-1.16), p = 0.09] and similar atrial tachyarrhythmia (ATA) recurrence rates [HR 0.70 (0.37-1.30), p = 0.26] over a median follow-up of 41 (24-71) months. ATA recurrence after the last procedure was associated with adverse events in the imp-EF group, whereas E-wave velocity was the only predictor in the pEF group in univariate analysis. CONCLUSIONS:Patients in both the imp-EF and pEF groups demonstrated comparable prognoses.

BACKGROUND:Coronary artery aneurysms (CAAs) rarely cause arrhythmias. CASE SUMMARY:A 64-year-old woman presented with palpitations. Electrocardiography revealed frequent monomorphic premature ventricular contractions (PVCs), with a rightward inferior axis and early transition in the precordial leads. Computed tomography identified a giant CAA in the proximal left anterior descending artery, adjacent to the left coronary cusp and the right ventricular outflow tract, with a fistulous connection to the pulmonary artery. Initial endocardial catheter ablation at the right ventricular outflow tract and left coronary cusp was ineffective. Surgical intervention including CAA resection, fistula closure, and epicardial cryoablation resulted in complete elimination of the PVCs. DISCUSSION:Giant CAAs, although rare, may serve as arrhythmogenic substrates for PVCs. Surgical intervention may be required for successful elimination of arrhythmias when catheter ablation fails. TAKE-HOME MESSAGES:This case demonstrates that giant CAAs may serve as arrhythmogenic substrates for PVCs. When catheter ablation fails, surgical management may provide a solution.

Duchenne muscular dystrophy (DMD) is a progressive myopathy caused by a mutation in the dystrophin gene. Cardiac disease is currently the leading cause of death in patients with DMD; thus, early diagnosis and management of cardiomyopathy are essential. Intra-voxel incoherent motion (IVIM) analysis provides quantitative values from diffusion-weighted imaging (DWI) and may serve as a novel index for evaluating myocardial properties in DMD. We conducted IVIM analysis in patients with DMD and compared their results with those of healthy volunteers to confirm that IVIM analysis can detect myocardial damage more effectively than conventional imaging methods. Patients with DMD who underwent cardiac magnetic resonance IVIM were enrolled. D and F values were measured using DWI of the left ventricle. Six healthy volunteers served as the control group. Twelve male patients with DMD were enrolled (median age, 14 years). Creatinine kinase levels were elevated, brain natriuretic peptide values remained within the normal range, and troponin T levels were only mildly elevated. The D value in patients with DMD was significantly higher than that in healthy volunteers, indicating increased diffusion in the myocardium (2.59 vs. 1.85, p = 0.0057); however, the F value was comparable between the two groups (0.62 vs. 0.61, p = 0.60). The D and F values from IVIM analysis provided a more detailed reflection of myocardial properties. Myocardial diffusion in patients with DMD was elevated compared with that in healthy volunteers.

BACKGROUND:Frequent premature atrial complexes (PACs) are associated with atrial fibrillation (AF); however, the temporal PAC frequency pattern preceding AF onset remains unclear. OBJECTIVE:This study aimed to evaluate whether PAC frequency increases before AF onset using long-term monitoring data from cardiovascular implantable electronic devices (CIEDs). METHODS:This retrospective study had 2 phases. In phase 1, a total of 101 patients with Boston Scientific CIEDs (mean follow-up 5.2 years) were divided into 2 groups: 48 who developed AF (age 68 ± 15 years) and 53 who did not (age 65 ± 15 years). AF was defined as any episode lasting >5.5 minutes. Daily PAC counts were derived from remote monitoring, and receiver operating characteristic analysis identified a threshold predictive of AF onset. In phase 2, in patients who developed AF, PAC frequency was compared across 3 time points: 1 year before AF onset, at onset, and 1 year after onset. RESULTS:In phase 1, median PAC count was significantly higher in the AF group than in the non-AF group (172.5 vs 21.1 PACs/d; P < .0001). A threshold of 31.8 PACs/d effectively ruled out AF presence (area under the curve 0.828; positive predictive value 71%, negative predictive value 97%). In phase 2, PAC frequency increased by 63% in the year preceding AF onset (105.7-172.5/d; P = .04) and remained elevated in the next year (P = .52). CONCLUSION:In our population of patients with CIEDs, those who developed AF had higher PAC frequencies, with a marked increase in the year before onset. A PAC burden of <31.8 PACs/d was rarely associated with future AF.

BACKGROUND:Ischemia with non-obstructive coronary arteries (INOCA) presents a diagnostic challenge as symptoms manifest in the absence of significant artery blockages. Myocardial strain ratio (MSR), derived from 13N-ammonia positron emission tomography (NH3-PET), can reportedly predict the prognosis of patients with ischemic heart disease. Consequently, in this study, we aimed to evaluate the prognostic value of MSR derived from NH3-PET in patients with INOCA. METHODS:We retrospectively analyzed 70 patients with INOCA who underwent adenosine-stress NH3-PET for suspected myocardial ischemia. INOCA was defined as typical angina without coronary stenosis. MSR was calculated as the ratio of strains at stress to strain at rest, determined by feature-tracking algorithms on PET images. The primary endpoint was major adverse cardiac events (MACE), including all-cause death, acute coronary syndrome, hospitalization for heart failure, and any coronary revascularization. We used Cox regression analysis to evaluate the predictive value of MSR for MACE. RESULTS:Receiver operating characteristic curve analysis identified an MSR cutoff of 0.94 for predicting MACE. Kaplan-Meier analysis revealed that patients with MSR < 0.94 had a higher incidence of MACE than those with MSR ≥ 0.94 (log-rank P = 0.027). Cox proportional hazards regression analysis confirmed MSR < 0.94 as an independent predictor of MACE in patients with INOCA. CONCLUSIONS:NH3-PET-derived MSR is a valuable marker for predicting adverse outcomes in patients with INOCA.