Pacemakers Could Aid More Heart Failure Patients

A new study suggests that patients with milder forms of heart failure (HF) can also be treated with a cardiac resynchronization therapy (CRT) device.

Researchers at the Karolinska Institutet (Stockholm, Sweden) conducted a study involving 25,171 patients (mean age 74.6 years, 39.9% women) in the Swedish Heart Failure Registry to determine the prevalence of, correlates with, and prognostic impact of QRS prolongation in HF with reduced and preserved ejection fraction (EF). The researchers assessed QRS width and 40 other clinically relevant variables, and the association between QRS width and all-cause mortality was analyzed. Prespecified subgroup analyses by EF were also performed.


The results showed that one-year survival was 77% in QRS over 120 ms, and 82% in QRS under 120 ms; 5-year survival was 42% and 51%, respectively. In all, 31% of the subjects had a QRS time longer than 120 ms. Strong predictors of QRS over 120 ms were higher age, male gender, dilated cardiomyopathy, longer duration of HF, and lower EF. There was no interaction shown between QRS width and EF. The researchers concluded that the study provides a rationale for trials of CRT in HF with preserved EF. The study was published early online on October 5, 2012, in the European Heart Journal.

“This advanced pacemaker has not yet been tried on heart failure caused by a reduced ability of the heart muscles to relax,” said lead author Lars Lund, MD, PhD, and colleagues of the department of medicine. “However, our results indicate that it could be valuable for this type of heart failure too, and this possibility is something that we must now go on to explore.”

A CRT device uses electrical impulses to maintain an adequate heart rate, because either the heart's native pacemaker is not fast enough or there is a block in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow the cardiologist to select the optimum pacing modes for individual patients. Some combine a pacemaker and defibrillator in a single implantable device. Others have multiple electrodes stimulating differing positions within the heart to improve synchronization of the ventricles.

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