May 9th, 2014

Routine Defibrillation Testing Not Required During ICD Implantation

Although commonly performed, routine defibrillation testing has never been shown to be safe or necessary. Now a new study, presented yesterday at the Heart Rhythm Society meeting in San Francisco, offers evidence that although routine testing is generally safe it may increase complications without producing any improvement in outcomes.

In the SIMPLE (Shockless Implant Evaluation) trial, sponsored by Boston Scientific and led by researchers at McMaster University in Hamilton, Ontario, 2,500 patients in 18 countries undergoing ICD implantation were randomized to routine defibrillation testing (DT) or no DT.

After three years of followup there was no significant difference in the primary endpoint of the trial, which was the rate of death due to arrhythmia or the failure of a first shock to terminate a lethal arrhythmia (7.2% in the no-DT arm versus 8.3%  in the DT arm, hazard ratio 0.86; CI 0.65-1.14,  non-inferiority p<0.001). There was no difference between the groups in total mortality.

The authors concluded that defibrillation testing “does not improve ICD shock efficacy or reduce mortality.” Although routine testing is “generally low risk,” complications may occasionally take place. Because of these facts, “the ‘no testing’ approach to routine ICD implantation should be preferred.”

“This is the first time the relationship between defibrillator testing and patient outcome has been studied independently in a randomized setting and with these results, we can confidently say that defibrillator testing, although safe, is not necessary at the time of ICD implantation,” said the lead author of the study, Jeff Healey, in a press release. “These results should change physician practice and could help reduce costs without compromising patient outcomes.”




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