Risk Stratification After Acute Myocardial Infarction by Heart Rate Turbulence

Abstract

Background-Retrospective postinfarction studies revealed that decreased heart rate turbulence (HRT) indicates increased risk for subsequent death. This is the first prospective study to validate HRT in a large cohort of the reperfusion era. Methods and Results-One thousand four hundred fifty-five survivors of an acute myocardial infarction (age Ͻ76 years) in sinus rhythm were enrolled. HRT onset (TO) and slope (TS) were calculated from Holter records. Patients were classified into the following HRT categories: category 0 if both TO and TS were normal, category 1 if either TO or TS was abnormal, or category 2 if both TO and TS were abnormal. The primary end point was all-cause mortality. During a follow-up of 22 months, 70 patients died. Multivariately, HRT category 2 was the strongest predictor of death (hazard ratio, 5.9; 95% CI, 2.9 to 12.2), followed by left ventricular ejection fraction (LVEF) Յ30% (4.5; 2.6 to 7.8), diabetes mellitus (2.5; 1.6 to 4.1), age Ն65 years (2.4; 1.5 to 3.9), and HRT category 1 (2.4; 1.2 to 4.9). LVEF Յ30% had a sensitivity of 27% at a positive predictive accuracy level of 23%. The combined criteria of LVEF Յ30%, HRT category 2 or LVEF Ͼ30%, age Ն65 years, diabetes mellitus, and HRT category 2 had a sensitivity of 24% at a positive predictive accuracy level of 37%. The combined criteria of LVEF Յ30% or LVEF Ͼ30%, age Ն65 years, diabetes mellitus, and HRT category 1 or 2 had a sensitivity of 44% at a positive predictive accuracy level of 23%. Conclusions-HRT is a strong predictor of subsequent death in postinfarction patients of the reperfusion era. (Circulation.

Simultaneous Assessment of T-Wave Alternans and Heart Rate Turbulence on Holter Electrocardiograms as Predictors for Serious Cardiac Events in Patients After Myocardial Infarction

“…8-11,14, 15 Patients after MI often have frequent paroxysmal ventricular contractions (PVCs), in which case it is difficult to assess TWA, including MMA-TWA, because the assessment is calculated using alternating change of T-wave morphology. In such cases, HRT is a useful tool because the assessment of HRT needs a number of PVCs.…”

Nonlinear Measures of Heart Rate Variability and Mortality Risk in Hemodialysis Patients

“…HRT estimates cardiac baroreceptor reflex function from the responses of NN intervals to putative transient arterial pressure reduction caused by ventricular premature contraction (VPC). The patterns of responses are classified into the following categories: normal (category 0), partially abnormal (category 1), and abnormal (category 2) (9,12,20). This measure is available only when .5 isolated VPCs suitable for the analysis are obtained from 24-hour electrocardiography.…”

“…DC calculated from short (four beats) overlapping segments is generally used. Currently, abnormal HRT and reduced DC are the most powerful predictors of post-MI mortality (9,10,12,13). Scaling exponents are calculated by detrended fluctuation analysis (11).…”

“…Clinically, three measures have gained recent interest: heart rate turbulence (HRT) quantifying heart rate responses to premature beats (9), deceleration capacity (DC) estimating ability to decelerate heart rate on specific time scales (10), and fractal scaling exponents assessing fractal organization of heart rate regulation based on chaos theory (11). Several studies have indicated that these nonlinear HRV measures have greater predictive power than conventional HRV measures for mortality after myocardial infarction (MI) (12)(13)(14). In hemodialysis patients, the nonlinear measures might have greater discrimination ability than conventional measures, because cardiac vagal dysfunction is almost commonly observed among these patients (15)(16)(17).…”

Nonlinear Methods of Cardiovascular Physics and Their Clinical Applicability

“…We therefore think that the HRV parameters with the optimal predictive values as well as other ECG-based risk stratifiers should be retrospectively determined and then compared to HRT measurements. Our observations [Wessel et al, 2004c] cast doubt on the conclusion of Barthel et al [2003] that HRT is the strongest ECG-based risk predictor.…”