Posted on 08/28/2011

Adverse effects of right ventricular pacing on the survival of ICD (implantable cardioverter-defibrillator) patients are long term, researchers from the Minneapolis Heart Institute at Abbott Northwestern Hospital explained, however, CRT (cardiac resynchronization therapy) lessens the impact.

The scientists presented their findings at the European Society of Cardiology (ESC) Congress August 28 in Paris, France. Lead author Robert G. Hauser, MD, said: "We were pleased to discover that the average patient, despite having severe left ventricular dysfunction, lived nine years after ICD implantation, which are the best results that we are aware of."

The researchers conducted a study to determine the predictors of survival in ICD patients and the effect of right ventricular pacing on survival. They evaluated all 1,395 ICD patients at Minneapolis Heart Institute aged 18 years or older with ejection fraction 35 percent or greater between 2000 and 2009. 673 of them had ICD-CRT and were paced in both lower chambers of the heart; 468 patients had single or dual chamber ICDs and most were paced in the right ventricle less than 10 percent of the time; and 59 had single or dual chamber ICDs and were paced in the right ventricle continuously.

They made the significant discovery that survival of CRT patients was similar to single and dual chamber ICD patients paced less than 10 percent of the time. Those, who were paced continuously in the right ventricle, did not live as long as either the CRT patients or the patients who were infrequently paced in the right ventricle.

"Pacing had an adverse effect on survival," said Hauser. We also found that if the right and the left side of the heart were paced in synchrony, the patients fared better."

Other factors associated with better survival rates include treatment with an ARB or ACE inhibitor, the patients' age (younger ones survived for longer), not having some underlying diseases, such as chronic kidney disease, peripheral arterial disease, and heart failure.

Hauser added: "If a patient has to be paced because of a slow heart rate, their outcomes will be better if both chambers of the heart are paced, rather than just the right side. Further, every effort should be made to treat these patients with an ACE inhibitor or an ARB."

SOURCE: Medical News Today