HRS.14: Testing ICDs during implantation isn’t necessary

Keep it simple, … Well, you know the rest. Physicians now can apply that advice to defibrillator testing of cardiac devices during implantation, based on results from the SIMPLE trial presented May 8 at the Heart Rhythm Society’s scientific session in San Francisco. The practice was found to be safe but unnecessary.

Jeffrey S. Healy, MD, director of arrhythmia services at Hamilton Health Sciences in Hamilton, Ontario, shared findings from the international SIMPLE (Shockless Implant Evaluation) study at the conference’s late-breaking clinical trials. SIMPLE researchers randomized 2,500 patients who were being implanted with implantable cardioverter-defibrillators (ICDs) to either receive defibrillator testing or not during the procedure.

Electrophysiologists routinely test defibrillators at the time of implantation to ensure their ability to detect and stop ventricular fibrillation. “Hundreds of thousands of defibrillators have been implanted in the United States,” Healy said at a press conference. “With these large numbers, there began to emerge very rare but potentially life-threatening and life-ending complications associated with testing.”

The primary outcome was a composite of failed appropriate shocks or arrhythmic death and a secondary outcome was all-cause mortality. They evaluated safety 30 days after implantation and followed the patients for an average 3.1 years. The study was designed as a noninferiority trial.

Healy said the patient population reflected those typically seen in practice.

“Defibrillation testing did not improve outcomes at all,” he said. “We clearly met our goal for noninferiority by a very wide margin.”

They found no difference in all-cause mortality between the two groups. Overall complication rates in both groups were low.

“ICD implantation without testing does not give up any of the benefit of the ICD,” he said. “We think implanting ICDs without routine testing should be the preferred approach now.”