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Asymptomatic PAD Carries High Mortality

BY BRUCE JANCIN

VIENNA -- Asymptomatic peripheral arterial disease diagnosed through routine screening in the offices of primary care physicians carries a high, 5-year mortality similar to that of symptomatic peripheral arterial disease, Dr. Curt Diehm reported at the annual congress of the European Society of Cardiology.

This finding from the large national German Epidemiological Trial on Ankle-Brachial Index (getABI) contains a key message for primary care medicine: The only way most such asymptomatic high-risk individuals are likely to be identified and placed on preventive therapy in a timely way is through systematic screening for peripheral arterial disease (PAD) carried out when they visit their primary care physician for some other reason, said Dr. Diehm, professor of internal medicine at the University of Heidelberg, Mannheim, Germany.

"PAD is too important to leave to specialists only," he declared.

The getABI study involved 6,880 unselected patients aged at least 65 years who were screened for PAD in 344 German primary care practices. Participating primary care physicians and nurses had been taught by getABI vascular specialists to accurately measure ABI, which Dr. Diehm called "the most effective, accurate, and practical method" for PAD detection. The test takes about 8 minutes and has 95% sensitivity.

The baseline prevalence of PAD by the ABI criteria advocated in American Heart Association/American College of Cardiology guidelines was 20.8%. Nearly 600 patients had symptomatic PAD. Another 835 had asymptomatic PAD with an ABI of less than 0.9, a condition for which the prognosis had not been well defined earlier.

All-cause mortality at 1, 3, and 5 years was significantly greater in patients with PAD than in those without it, while no significant mortality difference was seen between those whose PAD was symptomatic or asymptomatic (see graph).

Thus, one in five patients who visited their primary care physician was found to have PAD. And after 5 years, roughly one in five of these patients diagnosed with PAD--whether silent or symptomatic--was dead.

Asymptomatic PAD has often been taken lightly because of a mistaken belief that it is more benign than symptomatic PAD. But the high mortality documented in getABI dictates that once patients receive the diagnosis of PAD, even if asymptomatic, they need to be placed on the same aggressive pharmacologic regimen recommended for secondary prevention in coronary disease--a statin, ?-blocker, and antiplatelet therapy, Dr. Diehm said.

The German primary care physicians' performance in this regard was lackluster, as has historically been true worldwide for PAD. Indeed, only 56% of getABI participants with PAD were placed on antiplatelet therapy, 23% received a statin, and 25% got a ?-blocker.

"PAD patients are underdiagnosed, they are underestimated, and they are undertreated," Dr. Diehm said.

He took strong issue with the AHA/ACC guidelines on PAD (Circulation 2006;113:e463-654) on one point. The guidelines state that ABI is to be calculated for each leg based upon the ratio of the higher of the two systolic ankle pressures--that is, the posterior tibial and dorsalis pedis--over the average of the right and left brachial artery systolic blood pressures.

"In my opinion that is absolutely wrong, because if you take the higher value of the two ankle arteries you miss distal occlusions. For this study we took the higher value and got a PAD prevalence of 20.8%. If we'd used the lower of the two ankle pressure values, the disease prevalence comes to 34%. I am certain that recommendation will be changed before long," he said in an interview.

Discussant Dr. Don Poldermans stressed that PAD is a marker for global atherosclerotic disease, so when a patient is diagnosed with PAD it's worthwhile to screen for asymptomatic disease in other vascular beds.

In a Dutch study of 352 patients who presented with PAD only, additional screening revealed that three-quarters had polyvascular disease also involving the coronary arteries, aorta, and/or carotid arteries, said Dr. Poldermans, professor of cardiology at Erasmus University, Rotterdam, Netherlands. The ongoing getABI study is funded by Sanofi-Aventis and the German Ministry of Health.

When asked to comment on this story, Dr. John (Jeb) Hallett stated: "This is a landmark study pressing all primary care physicians to screen for peripheral arterial disease in patients older than 65... and to treat it before it becomes symptomatic. We screen for other chronic diseases, e.g. prostate cancer, that actually have a better five-year survival than PAD."

Dr. Hallett is medical director of the Roper Saint Francis Heart and Vascular Center in Charleston, South Carolina, and a Vascular Specialist associate editor.