Heart rate turbulence.

Survivors of acute myocardial infarction are at increased risk of sudden cardiac death. Recent trials have demonstrated that in selected high risk post-myocardial infarction patients mortality can be significantly reduced by implantation of an autonomic cardioverter defibrillator. Therefore, risk stratification strategies have gained increasing importance. Recently, a new method for risk stratification, coined heart rate turbulence, has been published. The method quantifies the physiological short term fluctuation of sinus rhythm cycle lengths following singular ventricular premature complexes. Heart rate turbulence is a consistent phenomenon in low risk patients with ischemic heart disease. The absence of this phenomenon indicates a significantly increased risk of subsequent mortality. The measures for quantifying heart rate turbulence, turbulence onset, and turbulence slope are strong risk predictors, even when adjusted for other established mortality predictors, such as left ventricular ejection fraction, arrhythmia count, heart rate variability, mean heart rate and history of previous myocardial infarction. Heart rate turbulence may be useful not only for risk prediction in post-myocardial infarction patients but also for risk prediction in other patients such as in patients with dilated cardiomyopathy and Chagas disease.