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Sleep-Disordered Breathing Tied to Nocturnal Arrhythmia

Ventricular arrhythmias mainly occur between midnight and 6 a.m. in patients with ICDs

WEDNESDAY, June 1 (HealthDay News) -- Patients with an implantable cardioverter-defibrillator (ICD) who suffer from sleep-disordered breathing (SDB) may have an increased risk of life-threatening ventricular arrhythmia during sleep hours, according to a study published in the May issue of Heart Rhythm.

Tawfiq Zeidan-Shwiri, M.D., from the Rambam Medical Center in Haifa, Israel, and colleagues investigated the association between SDB and timing of life-threatening ventricular arrhythmias in 45 patients with ICDs, and established arrhythmic substrates. Participants underwent an overnight sleep study to identify SDB, defined as an apnea-hypopnea index of more than 10 events per hour. During a one-year follow-up, appropriate ICD therapy, defined as antitachycardia pacing or shock for ventricular tachycardia or ventricular fibrillation, was the main outcome studied.

The investigators identified SDB in 26 patients. SDB was identified as a predictor of any appropriate ICD therapy (odds ratio [OR], 4.4), and patients with SDB had higher appropriate ICD therapies compared to those without (73 versus 47 percent). Patients with SDB were at an increased risk of ventricular arrhythmia, primarily due to increased events between midnight and 6 a.m. (OR, 5.6), with no significant effect on appropriate ICD therapy during nonsleeping hours (OR, 0.7; P = 0.61).

"Patients with an ICD and SDB have a striking increase in the onset of life-threatening ventricular arrhythmic events during sleeping hours. These findings provide a rationale for SDB screening in patients with appropriate ICD therapy if device interrogation reveals a predominance of nocturnal onset of arrhythmias," the authors write.

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