The genetic influence on arrhythmia risk in hypertrophic cardiomyopathy (HCM) remains unclear.In this retrospective HCM cohort analysis, pathogenic genetic variants were associated with higher rates of ventricular tachycardia and poor sinus rhythm maintenance in atrial fibrillation.This finding suggests a need for tailored diagnostic and therapeutic approach for arrhythmia based on individual genetic profile in HCM patients.

Background: Mahaim fibers are accessory pathways (APs) known for their unique slow, exclusively antegrade decremental conduction and absence of retrograde conduction.Typically, Mahaim-type APs are located on the right side, with atrial insertion points at various locations along the tricuspid annulus.However, left-sided Mahaim fibers have been reported occasionally.Case presentation: A 30-year-old man with a structurally normal heart presented with wide complex tachycardia characterized by right bundle branch block (RBBB) morphology and left axis deviation, resembling ventricular tachycardia (VT).However, his young age, structurally normal heart, and the tachycardia's responsiveness to adenosine raised suspicion for antidromic atrioventricular reentrant tachycardia (AVRT).An electrophysiological study confirmed the diagnosis, identifying a left-sided decrementally conducting Mahaim like pathway as the underlying mechanism.While wide QRS tachycardia with RBBB morphology, left axis deviation, and no baseline preexcitation is often mistaken for VT, this case represented a notable exception.Conclusions: We described a rare mechanism of wide-complex tachycardia resulting from antidromic AVRT involving a left-sided Mahaim-like pathway which was successfully abated along the posterior mitral annulus.

Cardiac resynchronization therapy (CRT) is an effective treatment option for heart failure with left ventricular (LV) dyssynchrony.However, about one-third of patients do not respond to CRT.Computer simulation using in silico 3-dimensional (3D) electromechanical heart models is a method for predicting the efficacy of CRT in individual patients.We performed in silico CRT simulations using 3D electromechanical heart models able to reproduce electrophysiological heart diseases.We can screen the non-responders and predict the optimal LV lead position for CRT using this CRT in silico computer stimulation model.

Although novel cryoballoon ablation systems like PolarX are widely used, clear advantages over previous cryoballoon technologies have not been demonstrated.In this study, PolarX showed no significant difference in atrial fibrillation (AF)/atrial tachycardia recurrence compared to the Arctic Front cryoballoon system in patients with paroxysmal AF (hazard ratio [HR], 1.23; 95% confidence interval [CI], 0.63-2.42;P = 0.546), but significantly reduced recurrence in those with persistent AF (HR, 0.45; 95% CI, 0.24-0.99;P = 0.022).These findings suggest that, in patients with persistent AF, selecting a specific cryoballoon system like PolarX may lead to better procedural outcomes.

Background: Left bundle branch area pacing (LBBAP) represents an advanced physiologic conduction system pacing technique.However, the long-term stability of stylet-driven leads (SDLs) in LBBAP remains uncertain, with limited documented reports on lead fractures.Case presentation: An 81-year-old male with a history of chronic kidney disease, heart failure, and paroxysmal atrial fibrillation (AF) was admitted for medical management.The patient experienced persistent dyspnea and dizziness attributable to bradycardia and required ongoing rhythm control medication for paroxysmal AF.Given the presence of an underlying left bundle branch block with a mildly reduced left ventricular ejection fraction, a dual-chamber pacemaker (Enitra 8 DR-T; Biotronik, DDDR) with LBBAP using SDL (Solia S50) was implanted.As the patient underwent dialysis via the left arm, pacemaker implantation was performed through the right axillary vein.At 30 months post-implantation, elevated lead impedance exceeding 2,000 and complete ventricular lead dysfunction were highly suggestive of lead fracture despite fluoroscopic imaging showing no definitive evidence of fracture.During ventricular lead extraction, severe adhesions and right axillary vein obstruction were encountered, requiring an 11Fr TightRail device for successful removal.The extracted lead displayed a distinct bend near the interelectrode segment, confirming a typical SDL fracture in LBBAP.Conclusions: This case highlights the typical characteristics of lead fracture and precautions associated with SDL-LBBAP and emphasizes that such fractures can occur beyond previously reported timeframes.To prevent SDL-LBBAP fracture, careful attention to lead manipulation during rotational adjustments is essential during the procedure.

Right ventricular apical or outflow-tract pacing is non-physiological, conferring longterm deleterious effects; His-bundle (HB) pacing (HBP) is more physiologic but elaborate requiring extra tools.Parahisian pacing (PHP), adopted by us for ~20 years, is an effective/ practical option, with the pacing lead placed near the HB or the proximal right bundle branch guided by fluoroscopy and electrocardiography, seeking a narrow-paced QRS by actively fixing the electrode across the tricuspid valve, against its septal leaflet.Comparative trials report that nonselective and selective HBP appear comparable regarding left-ventricular function, death or hospitalization.More comparative data with other pacing approaches are needed before PHP is widely adopted.