Criteria for selecting ARVD/C patients at highest risk
Date: December 26, 2011
Patients diagnosed with arrhythmogenic right ventricular dysplasia/cardiomyopathy—most of whom are young, healthy adults—are faced with an important decision: Should they have an implanted defibrillator for primary prevention of a life-threatening sustained ventricular arrhythmia?
To help determine which patients are at higher risk and most in need of an ICD, Hugh Calkins and colleagues evaluated the outcomes of 84 patients who participated in the Johns Hopkins ARVD/C Registry and underwent ICD implantation for sudden death prevention. Their goal was to identify which clinical variables placed those patients at highest risk of developing a sustained ventricular arrhythmia requiring treatment with their ICD.
Their analysis showed that four criteria are most useful in identifying high-risk ARVD/C patients. One of the criteria is whether a sustained irregular heart rhythm can be induced in the electrophysiology lab. Two criteria relate to findings on a Holter monitor—if a non-sustained ventricular tachycardia is recorded during the 24-hour monitoring and if more than 1,000 ectopic beats are recorded during the monitoring period. The fourth risk characteristic is whether the patient is the first in his family to be diagnosed with ARVD/C.
To test their criteria, the researchers studied the 84 patients who were diagnosed with either definite or probable ARVD/C. None had a history of sustained ventricular arrhythmias, but all had been given an implanted defibrillator as a precaution and were followed for an average of five years. During that time, 48 percent needed either a shock or rapid pacing from the device to stop a dangerous abnormal rhythm, while the remaining 52 percent did not experience an arrhythmia that required therapy from the defibrillator.
Patients in the study whose devices produced shocks or rapid pacing to stop abnormal rhythms generally met two or more of the criteria thought to put them at higher risk. None of the study participants who had either zero or one risk factor needed shocks or rapid pacing from their defibrillator to stop a life-threatening arrhythmia during the study period. However, 23 percent of those with two risk factors needed defibrillator therapy. The number increased to 65 percent among those with three risk factors and 78 percent for those with four risk factors.
“We found that there was an incremental and additive risk to these patients the more criteria they met,” says the study’s first author, Aditya Bhonsale. “So if a patient was found to match only one of the four criteria, that person was at lower risk. A patient who was positive on all four criteria was at highest risk.”
“ARVD/C is a mysterious form of cardiomyopathy that kills young people,” adds Calkins. “We are working hard to find answers and help patients and their physicians make decisions about therapy. We hope that this data will provide value to those who are engaging in those discussions.”