Combination of heart rate recovery, T-wave alternans associated with improved risk assessment

The combination of heart rate recovery and T-wave alternans was more predictive of risk for both CV mortality and all-cause mortality in a low-risk population, study results suggested.

Researchers enrolled 1,972 consecutive patients from the Finnish Cardiovascular Study referred for exercise stress tests in the analysis. T-wave alternans were monitored continuously throughout the tests, as was heart rate recovery. Patients were followed for a mean of 48 months.

According to the study results, 55 patients (2.8% of population, 47.4% of all deaths) died from CV causes, yielding an annual CV mortality rate of 0.7% for the population. Following a Cox regression analysis adjusting for common coronary risk factors, high exercise-based T-wave alternans and heart rate recovery <18 bpm yielded RRs for all-cause mortality: 5.0 (95% CI, 2.1-12.1) and CV mortality: 12.3 (95% CI, 4.3-35.3). High recovery-based T-wave alternans (>60 MCV) and heart rate recovery <18 bpm yielded RRs of 6.1 (95% CI, 2.8-13.2) for all-cause mortality and 8.0 (95% CI, 2.9-22.0) for CV mortality. The researchers also reported that prediction by heart rate recovery and T-wave alternans exceeded that of standard CV risk factors, both when predicted individually or in combination.

“A broad implication of the study finding is that routine exercise testing discloses increased risk for CV as well as all-cause death among patients with both depressed heart rate rhythm and abnormal T-wave alternans,” the researchers wrote. “In addition to improving predictivity, the combined assessment of heart rate rhythm and T-wave alternans may be useful in gaining insight into the pathophysiologic mechanisms on an individual patient basis that could help guide therapy.”

Leino J. Heart Rhythm. 2009;6:1765-1771.

A challenge for electrophysiologists has been the identification of patients at risk for sudden cardiac death. When accomplished, an ICD is often prescribed. This paper offers a combination of tests to predict not just arrhythmic events but rather overall and cardiac mortality. The problem now becomes what to do with the information in the absence of a prospectively studied intervention that will decrease the risk of these outcomes which are not necessarily arrhythmic. The combination of risk stratification tests clearly improves sensitivity and specificity; the next frontier is to find which ones provide the best predictive accuracy and whether intervention can change natural history.

– Andrew E. Epstein, MD

Cardiology Today Editorial Board member