Efficacy and feasibility of cryoballoon ablation for atrial fibrillation in patients with heart failure: A large-scale multicenter study.

INTRODUCTION: Data are limited regarding outcomes of cryoballoon ablation for atrial fibrillation (AF) in patients with heart failure (HF). This large-scale multicenter study aimed to evaluate the prognosis of patients with HF after cryoballoon ablation for AF. METHODS: Among 3655 patients undergoing cryoballoon ablation at 17 institutions, 549 patients (15%) (391 with paroxysmal AF and 158 with persistent AF) diagnosed with HF preoperatively were analyzed. Clinical endpoints were recurrence, mortality, and HF hospitalization after ablation. RESULTS: Most patients had a preserved left ventricular ejection fraction (LVEF) ≥ 50%. During a mean follow-up period of 25.7 months, recurrence, all-cause death, and HF hospitalization occurred in 29%, 4.0%, and 4.8%, respectively. Cardiac function on echocardiography and B-type natriuretic peptide (BNP) levels significantly improved postoperatively, and the effect was more pronounced in the nonrecurrence group. Major complications occurred in 33 patients (6.0%), but most complications were phrenic nerve palsy (3.6%). Although death and HF hospitalization occurred more frequently in patients with LVEF ≤ 40% (n = 73) and New York Heart Association (NYHA) class III-IV (n = 19) than other subgroups, the BNP levels, and LVEF significantly improved after ablation in all LVEF and NYHA class subgroups. High BNP levels, NHYA class, CHADS2 score, and structural heart disease, but not postablation recurrence, independently predicted death, and HF hospitalization on multivariate analysis. The patients with tachycardia-induced cardiomyopathy had better recovery of BNP levels and LVEF after ablation than those with structural heart disease. CONCLUSIONS: Cryoballoon ablation for AF in HF patients is feasible and leads to significantly improved cardiac function.

Atrial trigeminy induced at a specific pacing cycle length in a patient with residual pulmonary vein conduction gap.

We report a case of atrial trigeminy induced only at a specific pacing cycle length in a patient with residual pulmonary vein conduction gap.

"Nonsignificant" early repolarization pattern on postresuscitation ECG as a harbinger of impending electrical storm.

We report a 55-year-old man who was resuscitated from out-of-hospital cardiac arrest and subsequently developed three episodes of ventricular fibrillation (VF) on the same day. Early repolarization (ER) pattern was not significant (<0.1 mV) on postresuscitation ECG. However, ER pattern became evident (0.25 mV) before the onset of VF and then completely disappeared. The unusual dynamics of ER pattern observed in the present case could be called "masked" ER syndrome.

Effect of beta-blockade on quantitative microvolt T-wave alternans in 24-hour continuous 12-lead ECG recordings in patients with long QT syndrome.

BACKGROUND: The aim of study was to investigate effects of beta-blockade on microvolt T-wave alternans (TWA), a precursor of lethal arrhythmia, in patients with long QT syndrome (LQTS). METHODS: Eleven consecutive LQTS patients, types 1 (n = 6), 3 (n = 2), and "non-1, non-2, non-3" (n = 3) were enrolled. All patients underwent 24-hr continuous 12-lead ECG monitoring before and after initiation of beta-blockade therapy. TWA was measured using the modified moving average method. RESULTS: Seven (63.6%) of the 11 patients studied were symptomatic, with history of cardiac arrest or documented Torsade de Pointes (TdP) in 4 and syncope in three patients. After a median follow-up of 34 months, beta-blockade reduced the number of symptomatic patients to 1 with TdP (p < 0.02), in whom TdP frequency decreased from 25 events/60 months (0.42 event/month) to seven events/69 months (0.1 event/month). In association with this reduction in symptoms, peak TWA decreased by 47% in the cohort after a median of eight months of beta-blockade therapy [from 95 (74-130) to 50 (39.5-64.5) µV, p = 0.01]. All patients exhibited TWA ≥42 µV before beta-blockade therapy, which eliminated these episodes in four patients. Daily frequency of TWA ≥42 µV episodes decreased by 87% [from 15 (6-26) to 2 (0-5) episodes/day, p = 0.009]. CONCLUSIONS: This study is limited by the small sample size and is mainly hypothesis generating. TWA monitoring deserves further evaluation as a risk marker and a guide to therapy in LQTS patients in future large-scale studies.

Importance of over-reading ambulatory ECG-based microvolt T-wave alternans to eliminate three main sources of measurement error.

BACKGROUND: Ambulatory electrocardiogram (ECG)-based microvolt T-wave alternans values measured by the modified moving average method (MMA-TWA) can be disrupted by T-wave changes that mimic true repolarization alternans. METHODS: We investigated potential sources of measurement error by studying 19 healthy subjects (12 men; median age, 25) free of known heart disease with 36-month follow-up to establish freedom from significant arrhythmia or syncope. All participants underwent 24-hr continuous 12-lead ECG monitoring. Causes of automated MMA-TWA ≥42 µV episodes were classified based on visual inspection. RESULTS: A total of 2,189 episodes of automated MMA-TWA episodes ≥42 µV were observed in all subjects (peak MMA-TWA: median, 94 µV; interquartile range, 81-112 µV). All episodes included one or more beats with T-wave deformation which lacked "repeating ABAB pattern" and therefore were identified as TWA measurement error. Causes of such error were categorized as: (a) artifact [72.6% (1,589/2,189), observed in 19 (100%) subjects], more frequently in limb than precordial leads; (b) T-wave changes due to changes in heart/body position [25.5% (559/2,189), observed in 14 (73.7%) subjects], frequently observed in leads V1-2; and (c) postextrasystolic T-wave changes [1.9% (41/2,189), observed in 2 (10.5%) subjects]. CONCLUSIONS: Relying only on automated MMA-TWA values obtained during ambulatory ECG monitoring can lead to incorrect measurement of TWA. Our findings offer the potential to reduce false-positive TWA results and to achieve more accurate detection of true repolarization alternans.

Shift in the retrograde atrial activation sequence after radiofrequency catheter ablation in left variant atypical atrioventricular nodal reentrant tachycardia.

The role of left AV nodal (SVN) connections in the genesis of "left-variant" atypical atrioventricular nodal reentrant tachycardia (AVNRT) and those with multiple retrograde pathways remain unclear. We describe an unusual case of "left-variant" atypical AVNRT, where change in the retrograde earliest atrial activation site (REAAS) at the coronary sinus (CS) following radiofrequency catheter ablation (RFCA) was observed. Our observation suggests that the REAAS, that is, the left AVN connections, could participate in the formation of the reentrant circuit of "left-variant" atypical AVNRT. Furthermore, its atrial breakthroughs involved as a circuit of SVT could be (functionally) multiple.

Unusual manifestation of left ventricular electrical conduction delay on the surface 12-lead electrocardiogram in a patient with prior myocardial infarction.

We describe a 41-year-old man with a prior history of myocardial infarction, whose surface 12-lead electrocardiogram did not show typical left bundle-branch block pattern or wide QRS complex. However, electrophysiological study showed distinct left ventricular electrical conduction delays. The surface 12-lead electrocardiogram modified to the paper at 50 mm/s and double standard (20 mm equals 1 mV) revealed obvious notches of the terminal forces of the QRS in leads II, III, aVL, aVF, V3, V4, V5, and V6, these might be partially consistent with left ventricular electrical conduction delay in the scar lesion of the infero-posterior of the ventricle.

Interference dissociation during a baseline complete left bundle-branch block with advanced right bundle-branch block.

A 64-year-old woman presented to the hospital with a complaint of dyspnea on effort. The 12­lead electrocardiogram showed a baseline complete left bundle-branch block, in which the right bundle developed >2:1 block. The subsequent blocked sinus impulse resulted in a ventricular pause that caused the ventricular escape presenting as a QRS complex with right bundle-branch block pattern. However, some of them disclosed typical fusion beats and led to interference dissociation. Although other possibilities including Lenegre's disease or myocardial disease were not excluded, the effective refractory period of both bundle branches degenerated by myocardial ischemia might be attributed to this rhythm.

Microvolt T-wave alternans monitoring in a patient with levofloxacin-induced Torsade de Pointes.

We present the case of a 62-year-old woman with levofloxacin-induced Torsade de Pointes, in whom microvolt T-wave alternans was measured during acute hospitalization and when QT interval was dynamically changing, illustrating a means for monitoring proarrhythmia.

Sudden paradoxical QT-interval prolongation exacerbating T-wave alternans in a patient with type 3 long QT syndrome.

We report a case with type 3 congenital long QT syndrome, who exhibited a sudden paradoxical QT-interval prolongation during a progressive increase in heart rate, which exacerbated T-wave alternans.