Patients with Sleep-Disordered Breathing More Likely to Develop Nighttime Life-threatening Ventricular Arrhythmias

Results from a new study demonstrate a significant increase in the incidence of ventricular tachycardia (VT) and ventricular fibrillation (VF) among patients with an implantable cardiac defibrillator (ICD) and sleep-disordered breathing (SDB) compared to patients without SDB. The study, published in the May edition of HeartRhythm, the official journal of the Heart Rhythm Society, found an increase in appropriate ICD therapies among SDB patients that creates a rationale for SDB screening in patients with predominant nighttime ICD therapy. Analysis also further suggests that the severity of SDB correlates with the risk of nocturnal arrhythmias. Between August 2007 and March 2009, a total of 45 patients with an established arrhythmic substrate were recruited into the study. Patients with an ICD for either primary or secondary prevention of sudden cardiac death were prospectively studied at the Department of Cardiology at Rambam Medical Center in Haifa, Israel. An overnight sleep study was performed on all 45 patients and they were followed for one year in an outpatient clinic. The primary outcome measure was appropriate ICD therapy, defined as antitachycardia pacing or shock for VT or VF during one year of follow-up. Of the 45 patients, SDB was present in 26 (57.8 percent) patients. Appropriate ICD therapies were higher among patients with SDB and logistic regression identified SDB as an independent predictor of any appropriate ICD therapy. The risk for ventricular arrhythmias was higher in patients with SDB solely due to an increase in events occurring between midnight and 6 a.m. with no discernible effect on appropriate ICD therapy during non-sleeping hours. “Currently, there is limited data available with regard to the predictors of fatal arrhythmias in patients with an ICD,” stated lead author Tawfig Zeidan-Shwiri, MD, Ramban Medical Center Haifa, Israel. “Our study sought to find specific clinical data to help improve the safety and quality of life of patients living with an ICD, and the results indicate that the presence of SDB should be considered in all patients with appropriate ICD therapy. However, more studies are needed to assess whether treatment of SDB reduces the risk of appropriate ICD therapy.” SDB is likely to be present in a significant amount of patients with an ICD and avoidance of frequent shocks is important for these patients. This study establishes several potential clinical implications for SDB and patients with an ICD, including the justification for SDB screening in patients with appropriate ICD therapy primarily at nighttime. For more information about this trial, please visit www.heartrhythmjournal.com.