Effect of ramipril on walking times and quality of life among patients with peripheral artery disease and intermittent claudication: a randomized controlled trial. Journal of the American Medical Association 2013; 309: 453-460.

OBJECTIVE

The objective of the trial was to examine whether ramipril, an angiotensin-converting enzyme (ACE), improves walking distance and health-related quality of life in patients with peripheral artery disease (PAD) associated with claudication.

METHODS

The study enrolled 212 patients with risk factors and symptoms of PAD treated by conventional therapies at three centers in Australia. All patients had an ankle-brachial index (ABI) of less than 0.90 at rest and intermittent claudication in at least one leg, which were stable for at least 6 preceding months along with the medication regimen. The patients were excluded if blood pressure was not controlled (brachial blood pressure of 160/100 mmHg or greater); if there was current or recent use of either ACE inhibitors or angiotensin II receptor blockers, potassium-sparing diuretics, or potassium supplements; renal failure (serum creatinine level 2.3 mg/dL or greater [200 µmol/L]); renal artery stenosis; previous coronary or peripheral artery revascularizations, recent myocardial infarction and other health conditions other than PAD that could adversely influence walking ability at the time of screening and for 1 year thereafter.

METHODS

This was a randomized, placebo-controlled, triple blinded study of ramipril at the high daily dose (10 mg) for 6 months. Primary outcomes were pain-free and maximum walking times assessed by a standard treadmill exercise test. Secondary outcomes were ABI changes; symptoms and functional status assessed by the Walking Impairment Questionnaire (WIQ)(1); health-related quality of life assessed by the Short-Form 36 Health Survey (SF-36)(2); and stenosis severity assessed by duplex ultrasound of the lower limb arteries. At baseline and at follow-up, pain-free and maximum walking distances were assessed by the standard constant load treadmill exercise test performed at a speed of 3.2 km/h and a grade of 12%.(3) ABI was calculated in both legs. Duplex ultrasonography was used to determine stenosis in lower-limb vessel segments. Functional changes per WIQ, and perceived disability assessed on the Physical Component Summary and the Mental Component Summary of the SF-36 were self-reported. Sample size was calculated as 100 patients per each group needed to provide a power of 80% at an α of 0.05 to detect a 120-second change in walking time and a 65-second change in pain-free walking time. A two-sided p-value of less than 0.05 was considered significant. Baseline variables were compared using the χ(2) test and one-way analysis of variance. The analysis of covariance model with baseline and post-treatment values after 6 months used Kruskal-Wallis analysis of variance. Imputations for missing 6-month data were performed. Data were analyzed on the intention-to-treat basis.

RESULTS

Of 921 potential participants screened, 212 eligible participants were randomized into equal-sized ramipril and placebo groups where baseline parameters were not different. Compliance was monitored by pill count and adverse effects were monitored through interval clinical assessments, laboratory tests, and telephone calls. There was a 100% adherence rate to the study medications among 200 patients who completed the study. Ramipril was associated with a 75-second increase in mean pain-free and a 255-second increase in maximum walking time. There was a modest (less than 5 mmHg) blood pressure reduction and a small (0.1) ABI increase at rest and after exercise compared to placebo. The maximum walking time increase after ramipril therapy compared to placebo was greater in the subgroup of patients with femoropopliteal disease (286 seconds) than in those with aortoiliac disease (127 seconds). Patients treated with ramipril showed improvement of the median distance, speed and stair climbing scores on the WIQ, as well as of the Physical, but not the Mental, Component Summary score on the SF-36. The most frequent side effect was dizziness, more common in the ramipril (8.5%) than in the placebo (2.8%) group. Persistent cough occurred in 6.6% of patients on ramipril, causing their withdrawal from the study.