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IntroductionPulmonary vein isolation (PVI) is an important treatment for atrial fibrillation (AF). However, many patients need more than one procedure to maintain long-term sinus rhythm. Even after two PVIs some may suffer from AF recurrences. We aimed to identify characteristics of patients who fail after two PVI procedures.Methods and resultsWe included 557 consecutive patients undergoing a first PVI procedure with a second-generation 28 mm cryoballoon. Follow-up procedures were performed using radiofrequency ablation targeting reconnected PVs only. Recurrent AF was defined as any episode of AF lasting >30 s on ECG or 24 hour Holter monitoring performed at 3, 6 and 12 months post procedure. Mean age was 59.1±10.2 years, 383 (68.8%) were male, 448 (80.4%) had paroxysmal AF and the most common underlying condition was hypertension (36.6%). A total of 140/557 (25.1%) patients underwent redo procedure with PVI only. Of these patients 45 (32.4%) had recurrence of AF. These patients were comparable regarding age and sex to those in sinus rhythm after one or two procedures. Multivariate logistic regression showed that non-paroxysmal AF (OR 1.08 (95% CI 1.01 to 1.15), estimated glomerular filtration rate (OR 0.96, 95% CI 0.94 to 0.99), bundle branch block (OR 4.17, 95% CI 1.38 to 12.58), heart failure (OR 4.17, 95% CI 1.38 to 12.58) and Left Atrium Volume Index (OR 1.04, 95% CI 1.01 to 1.08) were associated with AF recurrence after two PVIs. The area under the curve for the identified risk factors was 0.74.ConclusionsUsing a PVI-only approach, recurrence of AF after two AF ablation procedures is associated with more advanced underlying disease and persistent types of AF.

Amiodarone is frequently associated with thyroid dysfunction. Identifying predictors for amiodarone-associated thyroid dysfunction and assessing treatment outcome may aid clinicians in daily practice.We included 303 consecutive patients with amiodarone therapy for cardiac arrhythmias (260 with atrial fibrillation and 43 with ventricular arrhythmias). Thyroid function tests were performed every 6 months.Mean age was 63 ± 12 years and 66% was male. After median follow-up of 3·3 (0·1-24) years, 23 (8%) patients developed amiodarone-associated thyrotoxicosis (incidence rate 1·9 per 100 person years) and 18 (6%) hypothyroidism (incidence rate 1·1 per 100 person years). The only predictor for amiodarone-associated thyrotoxicosis was age62 years [HR = 2·4 (95% CI 1·0-5·7), P = 0·05]. Predictors for amiodarone-associated hypothyroidism were thyroid stimulating hormone1·4 mU/l at baseline [HR = 5·1 (95% CI 1·1-22·4), P = 0·03], left ventricular ejection fraction45% [HR = 3·8 (95% CI 1·1-13·3), P = 0·04] and diabetes mellitus at baseline [HR = 3·3 (95% CI 1·1-10·3), P = 0·04]. Gender was not a predictor for amiodarone-associated thyroid dysfunction. Five out of 12 (42%) patients with thyrotoxicosis exhibited spontaneous normalization of thyroid function on continuation of amiodarone therapy. Mean time to normalization in the total group was 6·2 ± 3·3 months, with no difference between continuing or discontinuing amiodarone (6·6 ± 3·8 vs 5·8 ± 2·8 months, P = 0·5).During median follow-up of 3·3 years, the incidence of amiodarone-associated thyrotoxicosis was higher compared to hypothyroidism. Only general predictors for amiodarone-associated thyroid dysfunction were observed. Discontinuation of amiodarone did not influence treatment outcome.