Introduction: Atrial fibrillation (AF) is a common arrhythmia in patients with hypertrophic cardiomyopathy (HCM) and is associated with renal function deterioration. The protective effects of catheter ablation (CA) of AF on the renal function in HCM patients remains unsolved. Methods: From 2009 to 2020, 169 consecutive patients with HCM and AF (age 70±12, 87 males) were retrospectively evaluated. The estimated glomerular filtration rate (eGFR) was evaluated at the study enrollment or one month before the CA and reevaluated three months and 12 months later. Results: Among the 169 patients, 63 underwent CA of AF (ablation group) and the remaining 106 did not (control group). After propensity score matching, 45 pairs were matched. The baseline eGFR was similar between the two groups (P=0.83). During a mean follow-up period of 34±27 months, sinus rhythm was maintained in 36 (80%) patients after 1.7±0.8 ablation procedures. The eGFR significantly decreased from baseline to three months (P<0.01) and from baseline to one year (P<0.01) in the control group, while the eGFR in the ablation group was maintained both from baseline to three months (P=0.94) and from baseline to one year (P=1.00) after the CA. The change in the eGFR between baseline and 12 months was significantly smaller in the ablation group than control group (P<0.01). After a logistic regression analysis, CA of AF was the independent predictor of an improvement of eGFR (OR: 2.81; 95% CI: 1.08-7.36 P=0.04). Conclusions: CA of AF had a protective effect on the renal function in patients with HCM.

Background: Atrial flutter (AFL) is a large re-entrant circuit located in the right atrium. Anti-arrhythmic drugs (AADs) can provoke AFL with 1:1 atrioventricular conduction (AVC) to cause hemodynamic collapse. We elucidated the characteristics of patients with AFL exhibiting spontaneous 1:1 AVC. Methods: Fifteen patients (1:1 AFL group; 11 males, 52.4±13.7 years old) who documented AFL with 1:1 AVC were enrolled and compared to 77 patients without 1:1 AVC (Control group; 71 males, 68.1±10.9 years old). Results: The use of AADs was greater in the 1:1 AFL group than in the control group (60.0 vs. 14.3%, p < 0.001). AFL cycle length during maximum AVC was significantly longer in the 1:1 AFL group than in the control group (274.7 ± 37.0 vs. 220.4 ± 26.2 msec, p < 0.001). Among 1:1 AVC group, 9 patients had AADs and AFL cycle length was significantly longer during 1:1 AVC as compared with 2:1 AVC documented the other day (284.4 ± 41.3 vs. 233.3 ± 26.0 msec, p <0.001), suggesting enhancement effect of the AADs during 1:1 AVC. Remaining 6 patients who did not take AADs, 2 patients showed enlargement of the tricuspid annulus and 3 patients developed 1:1 AVC during exercise. Conclusions: In addition to the enhancement of AAD effect, prolonged AFL cycle length associated with enlargement of the tricuspid annulus and shortened refractory period of the AV node might increase the risk of 1:1 AVC during AFL. Keywords: atrial flutter, atrial flutter cycle length, tricuspid annulus. Atrioventricular node, atrioventricular conduction, anti-arrhythmic drug

A 65-year-old male underwent a second ablation procedure for recurrent paroxysmal atrial fibrillation (AF). Twelve-lead ECG during sinus rhythm exhibited biphasic and split P-wave with a prolonged duration, which called notched P-wave (NPW). Radio-frequency applica-tion in the coronary sinus (CS) resulted AF termination and elimination of triggering ectopy with NPW disappearance. The CS musculature which played a principal role in triggering and maintaining AF formed the NPW. In patients with repetitive recurrent AF after the estab-lishment of the PV isolation who exhibit NPW during sinus rhythm, the CS might be one of the arrhythmogenic sources of AF.