HOPE brings hope for the use of the ankle-brachial index as cardiovascular risk marker

Daniel Duprez*

Cardiovascular Division, University of Minneapolis, 420 Delaware Street SE, Minneapolis, MN 55455, USA

* Correspondence to: Tel: +1 612-624-4948; Fax: +1 612-626-4411
E-mail address: dupree007{at}umn.edu

Received 19 August 2003; accepted 28 August 2003

See doi:10.1016/j.ehj.2003.10.033for the article to which this editorial refers

In this issue Ostergren et al.1studied the prognostic importance of the ankle-brachial index (ABI) and the risk reduction by the ACE-inhibitor, ramipril of major cardiovascular events in patients with clinical as well assubclinical peripheral arterial disease.

The authors used a very simple method in the determination of the ankle-brachial index, namely either by using the Doppler technique in a limited number of patients, but merely by manual palpation of either the posterior tibial or the dorsalis pedis artery during deflation of the ankle cuff pressure. I would like to emphasize that the Doppler technique is still the golden standard for the determination of the ankle-brachial index and the diagnosis of peripheral arterial disease. The authors recognize that by digital palpation of ankle pulse to record blood pressure is relatively crude and therefore their results could are probably underestimating the true relationship between ABI and cardiovascular outcome if they had uses more sensitive methods such as ultrasound.

Unfortunately in the whole strategy of cardiovascular risk detection, less attention has been paid to the measurement of the ABI and therefore the presence of peripheral arterial disease has been underscored or not recognized.2Moreover a low ABI is a strong predictor of morbidity and mortality during the follow-up even in patients with no clinical symptoms of PAD.3,4

In patients with intermittent claudication a low ABI is associated with progression of atherosclerosis as well as disease of the small arteries.5Even in patients with a previous myocardial infarction or stroke and in patients referred for coronary angiography the occurrence of a low ABI has been shown to increase the risk further.6

In general an ABI equal or above 1.00 is considered as normal. In some studies an ABI above 0.9 is considered as normal. An ABI between 0.9 and 0.6 is considered as moderately pathologic and below 0.6 as severely pathologic. In patients with diabetes there is sometimes an elevated ABI due to the stiff calcified arteries of the lower limbs.

Despite the tremendous effort of looking into new cardiovascular risk markers to design new cardiovascular trials and study cardiovascular outcome of new drugs, one should recognize that a reduced ABI even in a asymptomatic patient as one of the inclusion criteria could be an important help in the increase of the cardiovascular risk and therefore less patients would be needed to be included in the trial to reach statistical power. In times of major health care budget burden, ABI can be utilized with little or no additional costs to further stratify patients into risk categories who may benefit to a greater extent by preventive treatments.

Another important finding is that in the presence of peripheral arterial disease, either subclinical or clinical, ACE-inhibitors reduce substantially cardiovascular morbidity and mortality in the presence or absence of hypertension. A follow-up of renal function is recommended.

In conclusion, ABI should be used to help define cardiovascular risk in patients with and without symptomatic cardiovascular disease and should also be considered in the planning of future large cardiovascular prevention trials.

References

  1. Ostergren JB, Sleight P, Dagenais G et al. Impact of ramipril in patients with evidence of clinical or subclinical peripheral arterial disease. Eur Heart J. 2004;25:17–24.[Abstract/Free Full Text]
  2. Hirsch AT, Criqui MH, Treat-Jacobson D et al. Peripheral arterial disease detection, awareness, and treatment in primary care. JAMA. 2001;286:1317–1324.[Abstract/Free Full Text]
  3. Leng GC, Fowkes FG, Lee AJ et al. Use of ankle brachial pressure index to predict cardiovascular events and death: a cohort study. BMJ. 1996;313:1440–1444.[Abstract/Free Full Text]
  4. Newman AB, Shemanski L, Manolio TA et al. Ankle-arm index as a predictor of cardiovascular disease and mortality in the cardiovascular health study. Arterioscler Thromb Vasc Biol. 1999;19:538–545.[Abstract/Free Full Text]
  5. Duprez DA, De Buyzere M, De Bruyne L et al. Small and large artery elasticity indices in peripheral arterial occlusive disease (PAOD). Vasc Med. 2001;6:211–214.[Medline]
  6. CAPRIE Steering Committee. A randomized , blinded, trial of clopidogrel versus aspirin in patients at risk for ischaemic events. Lancet. 1996;345:615–618.[CrossRef]

Related articles in EHJ:

Impact of ramipril in patients with evidence of clinical or subclinical peripheral arterial disease
J. Östergren, P. Sleight, G. Dagenais, K. Danisa, J. Bosch, Yi Qilong, S. Yusuf, and for the HOPE study investigators
EHJ 2004 25: 17-24. [Abstract] [Full Text]