Abnormal heart rate turbulence, an ECG-based risk marker, is a significant risk predictor for sudden death in patients with congestive heart failure (CHF), according to the MUSIC study published in the August edition of the Heart Rhythm Journal.
The MUSIC (Muerte Subita en Insufficiencia Cardiaca) study, a multi-center, Spanish, longitudinal study designed to assess risk markers for sudden death in CHF patients, represents the largest heart failure population ever studied, according to the researchers.
Principal investigator Antoni Bayes de Luna, MD, said this is the first study to document that heart rate turbulence predicts not only all-cause mortality and HF progression, but also sudden death in patients with HF.
In 651 CHF patients with sinus rhythm enrolled in the study, the researchers assessed standard heart rate turbulence parameters, such as turbulence onset and turbulence slope for predicting total mortality and sudden death. Holter monitoring was performed at enrollment to assess slope of the QTa/RR and QTe/RR as well as heart rate turbulence.
Heart rate turbulence was analyzable in 607 patients, mean age 63 years (434 male), 50 percent of ischemic etiology, the authors wrote.
During a median follow up of 44 months, 129 patients died—52 from sudden death. Abnormal turbulence onset and slope and heart rate turbulence category 2 were independently associated with increased all-cause mortality, sudden death, and death due to heart failure progression. The researchers found turbulence onset and slope to be predictive for total mortality only in patients with QRS > 120 ms.
“Our study documented that heart rate turbulence might be considered a useful tool to identify heart failure patients at high risk of death, including high risk of dying suddenly,” said lead author Iwona Cygankiewicz, MD, from the cardiology division at the University of Rochester Medical Center in Rochester, New York. “Heart rate turbulence may help physicians more effectively manage heart failure patients by indicating the need for more frequent follow up visits at specialized heart failure units and more intensely applied therapy, including ICD implantation in high risk patients.”
Approximately 50 percent of CHF-related deaths are due to progressive heart failure, while the other half are thought to be related to serious arrhythmias, according to the researchers. Even though heart rate turbulence was proven as an important risk stratifier in post-infarction patients, little is known about its value in patients with heart failure. Previous, smaller studies have proven abnormal heart rate turbulence as a risk stratifier for all-cause mortality and heart failure progression, but not sudden death.