COURAGE Analysis: Patients With Lower Exercise Capacity No More Likely to Benefit from Revascularization

Stable ischemic heart disease patients with low exercise capacity are not more likely to derive benefit from revascularization plus optimal medical therapy (OMT) vs OMT alone than their counterparts with higher exercise capacity, according to a post hoc analysis of the COURAGE trial published online August 31, 2015, in the American Journal of Cardiology.

The findings suggest that in this patient population “an initial strategy of multifaceted, aggressive lifestyle modifications, regular aerobic exercise to improve exercise capacity, and intensive medical therapy may decrease future cardiovascular events,” write William E. Boden, MD, of Samuel S. Stratton VA Medical Center (Albany, NY), and colleagues.

The main COURAGE analysis evaluated OMT—consisting of aggressive lifestyle modifications and intensive medical therapy—with or without PCI in patients with stable ischemic CAD. Results published in the New England Journal of Medicine in 2007 indicated that death and MI rates were equivalent in the 2 treatment arms.

For the post hoc analysis, the investigators looked at patients in both arms (mean age 61.4 years; 85% men) who were divided into lower or higher exercise capacity groups based on metabolic equivalents (METs) achieved during baseline treadmill testing:

• Lower: < 7 METs (n = 464)
• Higher: ≥ 7 METs (n = 588)

Compared with patients in the higher exercise capacity, those with lower capacity were older and more often female and had a higher resting systolic but a lower diastolic blood pressure. They were also more likely to have Canadian Cardiovascular Class II or III angina and  to have received calcium channel blockers but less likely to have a family history of CAD.

No Impact on Hard Outcomes

At a median follow-up of 4.6 years, rates of death or MI (primary composite endpoint) were similar between those assigned to PCI + OMT vs OMT alone, regardless of baseline exercise capacity (table 1).

The findings remained the same after adjusting for baseline covariates, with no signal of an interaction between the original treatment allocation and baseline exercise capacity.

Possible Explanations

Dr. Boden and colleagues note that prior studies have shown that patients with low exercise capacity are more likely to benefit from surgery. The lack of such a finding for PCI in COURAGE may be due to the fact that “the more aggressive use of OMT and intensive therapeutic lifestyle modifications may have offset the adverse effects of lower exercise capacity,” they write.

The difference also could be related to the mode of revascularization employed (CABG vs PCI) or the evolution of medical therapy over the past 2 decades, they add.

However, Dr. Boden and colleagues observe, due to multiple study limitations, it is unclear whether high-risk patients with impaired exercise capacity might in fact derive a greater clinical benefit from PCI in addition to OMT.

Source:
Padala SK, Sidhu MS, Hartigan PM. Effect of baseline exercise capacity on outcomes in patients with stable coronary heart disease (a post hoc analysis of the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation [COURAGE] trial). Am J Cardiol. 2015;Epub ahead of print.

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• COURAGE Substudy: PCI Adds No Overall Benefit to OMT Alone in Either Women or Men
• FAME 2: PCI Bests Medical Therapy in Stable Patients with Proven Ischemia
• COURAGE Substudy: Treat the Components, Not the Syndrome