By: 23 June 2014
Cut down on defibrillator testing, say researchers

New research from McMaster University suggests that a common test used during certain types of heart surgery is not helpful and possibly harmful.

Defibrillator testing (DT) is commonly used on people who require implantable cardioverter-defibrillators (ICDs) to prevent sudden cardiac death. It involves putting the patient into cardiac arrest to determine whether the defibrillator can first recognise, then successfully shock the patient back into a normal heart rhythm. It requires the use of general anaesthesia and is associated with uncommon but potentially life-threatening complications.

“As with many things in medicine, technology evolves and our knowledge grows and we have presented good evidence that the DT, which has been in use for nearly 30 years, is no longer necessary,” said lead author Jeff Healey, associate professor of medicine in the Michael G. DeGroote School of Medicine at McMaster University. “Without the testing we can save a significant amount of time, money and, more importantly, avoid potentially serious complications in patients who are receiving an ICD.”

Similar to a pacemaker, an ICD is a small battery-powered electrical impulse generator meant as a permanent safeguard against sudden arrhythmias. Each year, about 300,000 patients worldwide receive an ICD, and of these, approximately 70 percent undergo routine defibrillation testing that can lead to complications including possible harm from ICD shocks.

“Over the last 10 years, there has been an important shift in practice around the world towards ICD implantation without the test,” said Healey. “However, until now, there has been no scientific evidence to support this change in practice. Our study provides clear and robust evidence to guide practice.”

To test the procedure, Healey initiated a randomised trial, called the Shockless IMPLant Evaluation (SIMPLE) study, involving a cohort of 2,500 patients worldwide. The trial compared standard DT in a patient with those who do not undergo the testing and revealed that those who received ICDs without testing did as well as those who underwent the standard test.