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Walk test may serve as predictor for CV events
When used in conjunction with traditional risk factors, a 6-minute walk test was on par with treadmill exercise capacity and improved risk prediction in patients with stable CHD, according to data published in the Archives of Internal Medicine.
Specifically, distance walked during the test was associated with risk for adverse CV events.
Among the 556 participants included in the Heart and Soul Study, 39.2% experienced CV events. Rate of events was four times higher for patients in the lowest quartile of 6-minute walk test (6MWT) distance (87 m to 419 m) when compared with those in the highest quartile (544 m to 837 m), with an unadjusted HR of 4.29 (95% CI, 2.83-6.53).
Data also linked each standard deviation (SD) increase in 6MWT distance to a 55% higher rate of CV events (age-adjusted HR=1.55; 95% CI, 1.35-1.78). When analyzed according to event type, each increase in SD correlated with an 86% higher rate of HF (age-adjusted HR=1.86; 95% CI, 1.51-2.31); a 47% higher rate of MI (HR=1.47; 95% CI, 1.15-1.89); and a 54% higher rate of death (HR=1.54; 95% CI, 1.32-1.8). After adjustment for traditional risk factors and cardiac disease severity measures, such as ejection fraction, inducible ischemia, diastolic dysfunction, amino-terminal portion of brain-type natriuretic peptide (NT-proBNP) and CRP, each SD increase was associated with a 30% higher rate of CV events (HR=1.3; 95% CI, 1.1-1.53).
Adding 6MWT to traditional risk factors led to category-free net reclassification improvement of 39% (95% CI, 19-60). Further, the discriminative ability of the test was comparable to that of treadmill exercise capacity for predicting CV events (P=.29).
All participants were outpatients with stable CHD and were followed for a median of 8 years for CV events, including HF, MI and death.
Although the researchers said treadmill exercise testing is still preferable for assessing patients with suspected ischemia, the 6MWT has potential benefit. For instance, the test requires little equipment; adverse events experienced during the test are usually mild; and the 6MWT is considerably less expensive than treadmill exercise testing ($59.91 vs. $88.50, plus an additional $209 to $503 for imaging).
“The 6MWT may be a useful tool for measuring functional exercise capacity in patients with stable CHD to help target secondary prevention goals for physical activity,” the researchers concluded.
Disclosure: Study researcher Mary A. Whooley, MD, reports receiving research support from Gilead Sciences and Roche Diagnostics.