Statins Possibly Protect Against Death, CV Events in Asymptomatic PAD Patients

Patients with asymptomatic PAD and no signs of cardiovascular disease still stand to derive protection against death and cardiovascular events if they start taking statins, according to an observational study.

Importantly, the absolute reduction in risk is “comparable to that achieved in secondary prevention,” stress Rafel Ramos, MD, PhD, of the Jordi Gol Institute for Primary Care Research (Girona, Spain), and colleagues, who looked at patients whose ankle-brachial index (ABI) had been saved in the Catalan primary care system’s clinical records database between April 2006 and December 2011.

One possible lesson, the researchers say, is that “routine ABI screening for asymptomatic PAD in the targeted population could be a useful strategy to identify candidates for statin therapy, most of whom would not be considered candidates on the basis of risk functions.” In fact, an ABI of 0.95 or below—the cutoff in the current study—might be sufficient in and of itself to indicate statin use independent of other risk estimates, they suggest.

In all, 12,119 out of more than 74,000 patients in the database met inclusion criteria—namely, they had an ABI ≤ 0.95 (but ≥ 0.40), were not previously taking statins, had no previously known cardiovascular disease, and were aged 35 to 85 years. Patients were divided according to whether they were statin nonusers or new users, meaning that they were on their first prescription or being newly started after a gap of at least 6 months.

The researchers then identified 2,740 pairs that were matched by inclusion date and propensity for statin treatment. The 10-year predicted risk of coronary heart disease was low at a median of 6.9%. Median follow-up was 3.6 years. Approximately three-quarters of new users were on statins considered to have low or moderate LDL reduction capacity.

Risks of both MACE and all-cause mortality were lower for patients newly taking statins than for those not receiving the drugs.

The 1-year number needed to treat was 200 for MACE and 239 for all-cause mortality.

Compared with nonusers, patients taking statins had no greater risk of adverse events, though there was a nonsignificant trend toward more cases of new diabetes. Lack of statistical power might explain this lack of significance, the researchers caution, and there is the possibility “that mild myopathy or mild hepatopathy might be underestimated in electronic medical records.” Nor is it known what might happen with longer statin exposure, they add.

Ramos and colleagues conclude that the positive results, by virtue of being derived from observational data, “may not provide enough evidence to establish clinical recommendations, but they do justify the performance of RCTs to further elucidate this question.”

Most of These Patients Likely Statin Candidates Anyway

An accompanying editorial by Mary McGrae McDermott, MD, of Northwestern University Feinberg School of Medicine (Chicago, IL), and Michael H. Criqui, MD, MPH, of the University of California, San Diego School of Medicine (La Jolla, CA), expresses some skepticism, however.

Already, American Heart Association/American College of Cardiology (AHA/ACC) guidelines recommend using ABI to screen high-risk groups. Yet the US Preventive Services Task Force concluded in 2013 “that insufficient evidence exists to recommend for or against ABI screening as a cardiovascular risk assessment in adults,” they point out.

The current study is unlikely to change clinical practice, given that AHA/ACC guidelines already say people with PAD should receive cholesterol-lowering therapy—with no requirement that they be symptomatic—and also recommend statins for most people with diabetes and others at high risk for atherosclerotic disease, the editorialists say.

“Widespread ABI screening could be potentially useful if it identified a large number of individuals with a low ABI who would otherwise not qualify for cholesterol-lowering therapy,” they write. Yet the current study did not address this scenario, given that, for example, approximately 72% of matched patients had diabetes. “However, available evidence suggests that the number of people with a low ABI and no other indication for cholesterol-lowering therapy is small,” they report. “Therefore, the results reported by Ramos et al should not be construed as justifying widespread ABI screening.”

That being said, the association between statin use and adverse events seen here is “strong,” and there are likely other potential benefits of ABI screening, McDermott and Criqui admit, such as “potentially clarifying vague leg symptoms such as numbness, weakness, and fatigue, as well as the identification of additional CVD risk that might motivate better adherence to therapy.”

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Source: 
1. Ramos R, García-Gil M, Comas-Cufí M, et al. Statins for prevention of cardiovascular events in a low-risk population with low ankle brachial index. J Am Coll Cardiol. 2016;67:630-640.
2. McDermott MM, Criqui MH. Reducing cardiovascular risk with ankle brachial index screening: new evidence for an old question [editorial]? J Am Coll Cardiol. 2016;67:641-643.

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