The risk profile for obstructive sleep apnea does not affect the recurrence of atrial fibrillation.

BACKGROUND: Obstructive sleep apnea (OSA) has been linked to increased prevalence and recurrence of atrial fibrillation (AF). We hypothesized that OSA may aggravate AF in patients with pacemakers implanted for sinus bradycardia who had documented paroxysmal AF. METHODS: Seventy-two patients (36 M, aged 77 +/- 6 years) completed the study. All patients received a dual-chamber pacemaker equipped with diagnostic and preventive functions for AF. OSA was diagnosed with the Berlin Questionnaire, which is validated to identify patients with OSA. Four-month continuous pacemaker recordings were collected for all patients. RESULTS: OSA was diagnosed in 28% of patients. Patients at high risk for OSA (HR group) and patients at low risk for OSA (LR group) were equivalent for gender, age, and body mass index. The rate of hypertension was higher in HR than in LR group (90% vs 44%, P < 0.01). The prevalence of paroxysmal AF during the study period was similar in HR and LR group (53% vs 44%, P = NS). Overall number of AF episodes per month was not significantly different between HR and LR group (7 +/- 13 vs 36 +/- 122, P = NS). Similarly, AF burden (AF%) was not significantly different between HR and LR group (0.3 +/- 0.6 vs 2.0 +/- 4.8, P = NS). Circadian distribution of AF episodes was similar in both groups. CONCLUSION: Long-term pacemaker recording of AF recurrence, AF burden, and its circadian distribution is similar in patients with paroxysmal AF at high risk for OSA and those at low risk for OSA.

Clustering of ventricular tachyarrhythmias in heart failure patients implanted with a biventricular cardioverter defibrillator.

BACKGROUND: Temporal patterns of ventricular tachyarrhythmia (VT/VF) have been studied only in patients who have received implantable cardioverter defibrillators (ICD) for secondary prevention of sudden death, and mainly in ischemic patients. The aim of this study was to evaluate VT/VF recurrence patterns in heart failure (HF) patients with biventricular ICD and to stratify results according to HF etiology and ICD indication. METHODS AND RESULTS: We studied 421 patients (91% male, 66 +/- 9 years). HF etiology was ischemic in 292 patients and nonischemic in 129. ICD indication was for primary prevention in 227 patients and secondary prevention in 194. Baseline left ventricular ejection fraction (LVEF) was 26 +/- 7%, QRS duration 168 +/- 32 msec, and NYHA class 2.9 +/- 0.6. In a follow-up of 19 +/- 11 months, 1,838 VT/VF in 110 patients were appropriately detected. In 59 patients who had > or = 4 episodes, we tried to determine whether VT/VF occurred randomly or rather tended to cluster by fitting the frequency distribution of tachycardia interdetection intervals with exponential functions: VT/VF clusters were observed in 46 patients (78% of the subgroup of patients with > or = 4 episodes and 11% of the overall population). On multivariate logistic analysis, VT/VF clusters were significantly (P < 0.01) associated with ICD indication for secondary prevention (odds ratio [OR] = 3.12; confidence interval [CI] = 1.56-6.92), nonischemic HF etiology (OR = 4.34; CI = 2.02-9.32), monomorphic VT (OR = 4.96; CI = 2.28-10.8), and LVEF < 25% (OR = 3.34; CI = 1.54-7.23). Cardiovascular hospitalizations and deaths occurred more frequently in cluster (21/46 [46%]) than in noncluster patients (63/375 (17%), P < 0.0001). CONCLUSIONS: In HF patients with biventricular ICDs, VT/VF clusters may be regarded as the epiphenomenon of HF deterioration or as a marker of suboptimal response to cardiac resynchronization therapy.