June 18 (UPI) -- People at a risk for heart failure often turn to a defibrillator to remove that threat, but for some patients that's not always the answer, new research shows.
For patients with heart abnormalities that can't be fixed with a normal defibrillator, a cardiac resynchronization therapy with defibrillator may help with the problem, according to a study Monday in the Journal of the American College of Cardiology.
"CRT is known to improve heart function in patient with left bundle branch block, but until now we have not had enough evidence to support use of CRT in patients with either right bundle branch block and nonspecific intraventricular conduction delay," lead author Hiro Kawata, a researcher at Oregon Heart and Vascular Institute and, said in a news release.
Traditionally, research has focused on heart patients with left bundle branch block, which slows the activation of the heart's left ventricle.
This study discusses how CRT-D helps right bundle branch block and nonspecific intraventricular conduction delay (NICD), which combined are known as non-LBBB.
CRT-D works like a normal defibrillator, or ICD, in modulating heart rhythms when they beat too fast or slowly. But it also helps synchronize the contraction of the left and right ventricles by sending them little electrical shocks.
For the study, the researchers compared the QRS of the RBBB and NICD. QRS are EKG waves that show the time it takes for electricity to travel through the heart's lower ventricle. Abnormal conduction is any QRS longer than 120 milliseconds.
To gauge these results, the researchers looked at nearly 6,000 Medicare-aged patients implanted with a defibrillator who had either NICD or RBBB. They found the CRT-D was linked to a decrease in risk of death and hospital readmission for patients with NICD and a QRS higher than 159 milliseconds. Those outcomes are compared to those in patients who used ICD's.
However, CRT-D was not associated with better health results for patients with RBBB.
"Current guidelines state that when patients with heart failure and non-right bundle branch block conduction disorder continue to suffer symptoms such as shortness of breath or fatigue even after medical therapy, CRT can be tried as a next step, even though there is a lack of evidence about its effectiveness in these patients. We wanted to find out whether CRT can help non-LBBB patients," Kawata said.