Abstract

INTRODUCTION:

Submaximal exercise testing can be useful for individuals with limitations to performing maximal exercise. Recent studies suggested that a low workload at a heart rate 100 beats/minute (HR(100)) was associated with a greater risk of cardiovascular (CV) mortality than maximal exercise capacity. This study evaluated the prognostic value of METs achieved at HR(100) (METs(100)) in patients referred for treadmill testing.

METHOD:

We studied 1446 patients (56+/-12 years; 76 females) without heart failure or beta-blockers treatment (1997-2004).

RESULTS:

During a period of 7.0+/-2.3 years, 35 (2.5%) patients died from CV causes. Compared to survivors, the non-survivors were older (69+/-9 vs. 56+/-12 years, p<0.001); had a higher prevalence of diabetes (27% vs. 14%, p=0.04), coronary artery disease (57% vs. 25%, p<0.05) and stroke (9% vs. 2%, p<0.001). Non-survivors had lower Duke Treadmill Scores (DTS) (2.8+/-6.8 vs. 9.7+/-5.5; p<0.001) and exercise capacity (7.5+/-3.3 vs.11.0+/-3.8 METs, p<0.001). At HR(100), METs (median (range): 3.8 (2.8-4.0) vs. 3.5 (3.3-3.5)) and %HR reserve achieved (45+/-13% vs. 34+/-17%; p<0.001) were higher in non-survivors. In Cox model, age-adjusted METs(100) was not a significant predictor of CV mortality. In contrast, each one MET increase in exercise capacity was associated with a 17% increase in survival (HR=0.83, 95% CI 0.73-0.93, p=0.002). DTS was also a significant predictor of CV mortality.

CONCLUSION:

In our population, METs at HR(100) was not a significant predictor of CV mortality.

Copyright (c) 2008 Elsevier Ireland Ltd. All rights reserved.