A new study has found that there is a greater chance of surgical problems and death with implantable cardioverter-defibrillator (ICDs) that require leads attached to two chambers of the heart, compared to those that work on only one chamber.

Researchers at the University of Colorado (Boulder, USA) and the University of California, San Francisco (UCSF; USA) reviewed the US National Cardiovascular Data Registry to examine the association between baseline characteristics and device selection in 104,049 patients receiving single- and dual-chamber ICDs between January 1, 2006, and December 31, 2007; in all, dual-chamber devices were implanted in 64,489 patients (62%). A longitudinal cohort design was used to determine in-hospital complication rates in a large, real-world population.

The results showed that adverse events were more frequent with dual-chamber than with single-chamber devices (3.17% versus 2.11%), as was the rate of in-hospital mortality (0.40% versus 0.23%). After adjusting for demographics, medical comorbidities, diagnostic test data, and ICD indication, the odds of any complication and in-hospital mortality were increased with dual-chamber ICD implantation. The study was published in the August 30, 2011, issue of the Journal of the American College of Cardiology.

“There is no reason for alarm, and it's important to remember that defibrillators of all kinds have clearly-established benefits in terms of reducing mortality among patients at risk for sudden cardiac death,” said lead author Paul Varosy, MD. “But this study does suggest that the simpler defibrillators may cause fewer short-term problems, suggesting that the routine use of dual-chamber defibrillators even in the absence of a simultaneous need for a pacemaker should be reevaluated.”

Although dual-chamber ICDs offer theoretical advantages over single-chamber defibrillators, the clinical superiority of dual-chamber models has not been conclusively proven, and they may even increase complications, as this study suggests.

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