Pinpointing Deadly Arrhythmias

Arrhythmia patients may benefit from an implanted defibrillator

(RxWiki News) Heart arrhythmias can be life-threatening, though for some patients they're just a low-risk nuisance. A new set of criteria can help determine which patients are at risk for sudden death and would benefit from an implanted defibrillator.

Specifically, the criteria can be used to assess those that suffer from arrhythmogenic right ventricular dysplasia (ARVD), an inherited heart disorder that is a common cause of sudden death in athletes and young, healthy individuals.

"Ask your cardiologist if you could benefit from an implanted defibrillator."

Not all patients who have the disorder are considered high risk, but before the study there was little data available to decide which patients could benefit from defibrillator implantation.

Dr. Hugh Calkins, senior study author, a professor at Johns Hopkins University School of Medicine and head of cardiac electrophysiology at Johns Hopkins Medicine, said whether an ARVD patient should have an implantable defibrillator for primary prevention against sudden death is a critically important decision. He noted that most patients are young with few, if any symptoms, so the decision to implant a defibrillator that they would have the rest of their lives requires careful consideration.

ARVD creates scarring of the muscle, mainly on the right side of the heart, which interrupts the normal electrical activity of the heart, causing very fast, abnormal heart beats that prevent the heart from pumping blood to the rest of the body. The condition can be fatal without a shock from an external or implanted defibrillator.

Researchers enrolled 84 patients in the study with diagnosed or probable ARVD. All of the patients received implanted defibrillators and were followed for an average of five years. During the study period, 48 percent needed either a shock or rapid pacing from the device to stop a dangerous abnormal heart rhythm.

Four criteria were then established to determine which patients are at a higher risk and most in need of a defibrillator. Study patients whose devices produced shocks or rapid pacing met two or more of the criteria. Patients appeared to be a higher risk the more criteria they met, making those who met all four criteria at the highest risk.

The first criteria was whether a sustained irregular heart rhythm could be induced by a procedure in the electrophysiology lab. Two of the other criteria related to findings on a Holter monitor, which patients wear for 24 hours to monitor the electrical activity of the heart. The last was whether the patient was the first in the family to be diagnosed with ARVD.

None of the study participants who had zero or one risk factor needed shocks or rapid pacing, but 23 percent of those who met two criteria needed defibrillator therapy. That jumped to 65 percent with three risk factors and 78 percent if a patient had four risk factors.

The research was published in the Sept. 27 issue of the Journal of the American College of Cardiology.

Review Date: 
September 27, 2011