Prolonging ICD Shocks Safe

Less aggressive implantable cardioverter defibrillator programming effective

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) A potentially fatal abnormal heartbeat means some patients need an implanted device to provide a shock when dangerous rhythms are detected. Cardiologists describe the shocking sensation "like being hit with a baseball bat in the chest."

Doctors have pondered whether programming the implantable cardioverter defibrillators (ICDs) less aggressively could result in fewer painful shocks, while keeping patients just as safe.

"Talk to your cardiologist about ICD programming and safety."

Mohammad Saeed, MD, from the division of Cardiology at St. Luke's Episcopal Hospital, found that reprogramming ICDs to react less aggressively prolongs the amount of time until the first shock is delivered, but does not reduce effectiveness of the device or endanger patients. The research marked the first randomized trial to exam the safety and effectiveness of reprogramming ICDs.

During the Programming Implantable Cardioverter Defibrillators to Prolong Time to First Shock, or PROVIDE trial, 1,674 heart arrhythmia patients were enrolled at more than 100 centers.

The patients were an average age of 64 and most were men.

Within 30 days of having an ICD implanted, patients were randomly assigned to standard ICD programming or a less aggressive experimental level that featured higher detection rates, longer detection intervals, aggressive supraventricular tachycardia discriminators and extensive ATP therapy. Researchers then compared the time to first shock and incidence of arrhythmia-related fainting between the two groups over the 18-month follow up period.

Investigators found that the amount of time until the first shock in the experimental group was significantly longer than that of the standard group. Those in the experimental group also received 34 percent fewer shocks.

There was no statistically significant difference in arrhythmia-related fainting between groups, with 1.7 percent reported in the experimental group versus 1.2 percent in the other group.

In addition, researchers concluded that prolonging shocks was safe and did not increase the risk of arrhythmia-related fainting.

The findings were recently presented at Heart Rhythm 2012 in Boston, Mass.

Reviewed by: 
Review Date: 
May 11, 2012
Last Updated:
July 11, 2012