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Heart rate turbulence predicts death risk in HF patients
11 August 2008
MedWire News: Abnormal heart rate turbulence (HRT), a marker of autonomic nervous system dysfunction, is associated with an increased risk for both heart failure (HF) and arrhythmic death in patients with class II and III HF, a team reports.
"Our study documented that HRT might be considered a useful tool to identify HF patients at high risk of death, including high risk of dying suddenly," said lead author Iwona Cygankiewicz (University of Rochester Medical Center, New York, USA).
HRT could therefore identify high-risk patients who would benefit from more frequent follow-up visits at specialized HF units and more intensely applied therapy, including defibrillator implantation, Cygankiewicz added.
The MUSIC (Muerte Subita en Insufficiencia Cardiaca) Study, conducted in Spain, included 651 HF patients with sinus rhythm.
Cygankiewicz and team studied HRT data available for 607 patients, half of whom had ischemic disease. Specifically, they looked at the HRT parameters turbulence onset (TO), which reflects the initial phase of sinus rhythm acceleration, and turbulence slope (TS), which reflects the deceleration phase.
In all, 129 of these patients died over the median 44-month follow-up, the authors report in the journal Heart Rhythm.
Patients with an abnormal turbulence slope (TS) and those with both abnormal TO and abnormal TS had more than double the risk for all-cause mortality compared with patients in whom both parameters were normal, after adjusting for clinical covariates in multivariable analysis (both p<0.001).
Those with both abnormal TS and abnormal TO also had over twice the risk for sudden death (p=0.021) and four times the risk for death due to HF progression (p<0.001) compared with normal-HRT patients.
The authors note that TS predicted total mortality with similar ability in patients stratified by age, gender, HF functional class, ejection fraction, and HF etiology.
However, abnormal TS was more predictive in patients with wider than narrow QRS complexes.
"Wide QRS complex in CHF patients usually indicates more advanced disease process and, not surprisingly, patients with a wide QRS complex might have more advanced abnormalities of baroreflex sensitivity or autonomic regulation of the heart," the authors remark.
