REDEFINING THE INCIDENCE OF CLINICALLY DETECTABLE ATHEROEMBOLISM

BACKGROUND AND OBJECTIVES: Atheroembolism, caused by peripheral emboli zation of small cholesterol crystals that fracture off of ruptured ath erosclerotic plaques in the major vessels, leads to multifocal ischemi c lesions and progressive tissue loss. The end result is often ischemi c injury in the skin, kidney, brain, myocardium, and intestine, but an y organ distal to the culprit lesion may be affected. The precise inci dence of this serious clinical syndrome has been difficult to ascertai n from the available literature, but it appears to be much more common than has been assumed. The objective of the present study is to clari fy the incidence of atheroembolism among inpatients in an acute hospit al setting. PATIENTS AND METHODS: We surveyed inpatient nephrology con sultations during a 7-month period from January through July 1994. Fro m a pool of 402 consultation charts, 99 were identified with two or mo re substantive risk factors for atheroembolism. The records of 85 of t hese patients were available for careful review. More than 300 additio nal patients were found to have ICD-9 discharge codes for other vascul ar conditions, but we were unable to confirm that any of these were in fact cases of atheroembolism, since there is no specific ICD-9 discha rge code for this entity. In the 85 cases reviewed, a diagnosis of ath eroembolism was made only if the patient had identifiable substantive risk factors, suggestive physical findings, and supporting laboratory results. RESULTS: Eleven of the 85 surveyed records documented strong evidence supporting a ''probable'' diagnosis of atheroembolism. Tissue was examined in 4 of these 11, resulting in definitive histologic con firmation in 3. Another 5 of the 85 surveyed records were ''suggestive '' of atheroembolism. Altogether, atheroembolism was a likely diagnosi s in a total of 16 cases during this 7-month period, or 1 case every 2 weeks. These cases comprised 19% of nephrology consultations in which 2 or more risk factors were present, or 4% of all nephrology consulta tions. The patients' records confirmed the serious implications of cli nically detectable atheroembolism. Several patients underwent lower ex tremity amputation, nearly half required acute or chronic dialysis, an d more than half died within several months of diagnosis. CONCLUSIONS: The present study suggests that at least 4% of all inpatient nephrolo gy consultations, representing approximately 5% to 10% of the acute ve nal failure encountered, involve clinically significant atheroembolism . Patients with atheroembolism appear at a rate of at least 1 case eve ry 2 weeks. They often have identifiable substantive risk factors at i nitial consultation, and probably represent only the most severe cases of atheroembolism. In view of the serious implications of this basica lly untreatable syndrome, heightened awareness and preventive maneuver s in the population at risk are essential.