October 15, 2008 (Washington, DC) — Measurement of heart-rate turbulence (HRT), an ECG phenomenon that reflects hemodynamic responses to premature ventricular contractions (PVCs), can risk-stratify patients in the post-MI setting and may be similarly useful in heart failure or other heart disease, according to a state-of-the-art review in the October 21, 2008 issue of the Journal of the American College of Cardiology .
"Several large-scale retrospective and prospective studies have established beyond any doubt that HRT is one of the strongest independent risk predictors after MI. It thus appears that the stage has now been reached when HRT might be used in large prospective intervention studies," according to the authors, led by Dr Axel Bauer (Deutsches Herzzentrum, Munich, Germany).
The group had been asked to write the review by the International Society for Holter and Noninvasive Electrophysiology (ISHNE), it states.
HRT, first published as a potential CV risk stratifier in 1999 , and other measures of autonomic function aren't as well established or even studied as much as some other prognostic markers based on electrocardiography, such as T-wave alternans. As the authors note, it's usually measured from an average of multiple PVCs on 24-hour Holter monitoring. The baroreflex response is characterized on the Holter tracing by a brief acceleration in the heart rate after a PVC, followed by deceleration to a rate below the pre-PVC rate and then a return to baseline rate, they write.
The strongest support for the parameter's risk-stratification role comes from "six large-scale studies and from two prospective studies, both of which have been specifically designed to validate the prognostic value of HRT in post-MI patients receiving state-of-the-art treatment," the report states.
Other evidence suggests a role for HRT evaluation after PCI to assess the strength of perfusion from the treated coronary artery. "Persistent impairment of HRT after PCI in patients with incomplete reperfusion implies prolonged baroreflex impairment and is consistent with poor prognosis," write Bauer et al. "Thus, early assessment of HRT may be detecting pathological loss of reflex autonomic response due to incomplete reperfusion or severe microvascular dysfunction after PCI."
In heart failure, according to the authors, patients "are known to have significantly impaired baroreflex sensitivity as well as reduced heart-rate variability. . . . This may suggest the possibility of guiding pharmacological therapy [according to HRT responses] in heart-failure patients." They also note that the prognostic power of HRT in heart failure appears limited to patients with ischemic cardiomyopathy.
Bauer et al suggest that in the future, HRT be explored as a form of risk assessment in patients with diabetes but without clinical heart disease. "The same applies to patients with metabolic syndromes in whom easily accessible autonomic monitoring would have obvious clinical potential."
The report states that coauthor Dr Georg Schmidt (Deutsches Herzzentrum) "holds a patent on heart-rate turbulence."
Bauer A, Malik M, Schmidt G, et al. Heart rate turbulence: Standards of measurement, physiological interpretation, and clinical use. International Society for Holter and Noninvasive Electrophysiology consensus. J Am Coll Cardiol 2008; 52:1353–1365. doi:10.1016/j.jacc.2008.07.041
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Cite this: Current Risk-Stratification Role for Heart-Rate Turbulence Monitoring Defined - Medscape - Oct 15, 2008.