Catheter ablation of idiopathic ventricular arrhythmias（VAs）originating from the summit of the left ventricle（LV summit）can be challenging. There may be the communicating vein between the great cardiac vein and small cardiac vein which is located in close association with the LV summit（summit-CV）. We mapped the LV summit using a 2-Fr microcatheter introduced into the summit-CV. The site of origin was confirmed to be the LV summit near the summit-CV when the mapping catheter positioned in the summit-CV showed the earliest activation time during VAs with an excellent matching pacemap obtained by pacing at the location. The QRS morphology was characterized as an inferior axis with monomorphic R pattern in all inferior leads（taller R wave in leadIIIthan leadII）, a negative polarity in leadI, a QS pattern in leads aVR and aVL, and nonspecific bundle branch block morphology with an R/S ratio in lead V1 of 0.67±0.33. The ablation attempt was performed from the right/left ventricular outflow tract, aortic cusps, or great cardiac vein, whichever is earliest and/or closest to the microcatheter in the summit-CV. Overall, 10 patients（71％）were free from recurrent VAs during follow-up after their ablation procedure. A detailed mapping inside the summit-CV has the potential to localize the precise site of origin of LV summit VAs, which may serve as a landmark of the ablation target and facilitate ablation through adjacent structures.

The association between first-degree atrioventricular block（AVB）and life-threatening cardiac events in patients with hypertrophic cardiomyopathy（HCM）remains unclear. This study sought to investigate whether the presence of first-degree AVB was associated with HCM-related death in patients with HCM. We included 414 patients with HCM（mean age 51±16 years, 64.5％ men）. The P-R interval was measured at the time of the initial evaluation and patients were classified into those with and without first-degree AVB, which was defined as a P-R interval ≧200 milliseconds. HCM-related death was defined as a combined endpoint of sudden death or potentially lethal arrhythmic events, heart failure-related death, and stroke-related death. First-degree AVB was noted in 96 patients（23.2％）at the time of enrollment. Over a median（IQR）follow-up period of 8.8（4.9-12.9）years, a total of 56 patients（13.5％）experienced HCM-related deaths including 47（11.4％）with a combined endpoint of sudden death or potentially lethal arrhythmic events. In a multivariable analysis that included first-degree AVB and risk factors for life-threatening events, first-degree AVB was independently associated with an HCM-related death（adjusted hazard ratio［HR］ : 2.41 ; 95％ confidence interval ［CI］ : 1.27-4.58 ; p＝0.007）and this trend also persisted for the combined endpoint of sudden death or potentially lethal arrhythmic events（adjusted HR : 2.60 ; 95％ CI : 1.28-5.27 ; p＝0.008）. In this cohort of patients with HCM, first-degree AVB may be associated with HCM-related death, including the combined endpoint of sudden death or potentially lethal arrhythmic events.

Twiddler’s syndrome is a relatively rare complication after pacemaker implantation in which rotation of the pacemaker body results in displacement of the body and the lead, causing the pacemaker to malfunction. In this case report we present an 88-year-old female with dementia who developed Twiddler’s syndrome-like body and lead malposition after pacemaker implantation, but the pacemaker did not malfunction and required lead detachment because the lead was positioned in front of the body at the time of pacemaker battery replacement surgery.

Cardiac resynchronization therapy（CRT）has been used in patients with heart failure with intraventricular conduction delay, but left bundle branch pacing, which can provide physiological contraction through the native stimulatory conduction pathway, has attracted attention recently as a newer modality. The case described here was an 86-year-old male. He came to our hospital after suffering shorthness of breath for several days. His ECG showed complete left bundle branch block（LBBB, QRS duration of 146msec）and echocardiogram showed dyssynchrony. The patient was diagnosed with heart failure due to significant pulmonary congestion, but his subsequent treatment was poor. We report here a case of shortened QRS width, improved dyssynchrony, and recovery of cardiac function after left branch bundle pacing. In this case, we report the use of TomTec-Arena, a new evaluation method for dyssynchrony.