EXAGGERATED PRESSOR-RESPONSE TO TREADMILL EXERCISE IN CHRONIC COCAINE ABUSERS WITH LEFT-VENTRICULAR HYPERTROPHY

Background. Chronic cocaine abuse has been associated with a high prevalence of left ventricular hypertrophy (LVH) in normotensive individuals at rest. This study was conducted to determine whether chronic cocaine abusers with LVH would manifest an exaggerated pressor response to treadmill exercise. Methods and Results. Forty-nine normotensive chronic cocaine abusers underwent Bruce protocol treadmill exercise testing until they attained 85% maximum predicted heart rate. A peak exercise systolic blood pressure greater-than-or-equal-to 210 mm Hg was defined as abnormal. In addition, they underwent two-dimensional echocardiography and had left ventricular mass determined by the area-length method. LVH was defined as left ventricular mass greater-than-or-equal-to 105 g/m2 and a posterior wall thickness greater-than-or-equal-to 1.2 cm. Age- and race-matched control subjects also underwent echocardiography and exercise testing. Group differences in peak exercise blood pressure in cocaine abusers with LVH, cocaine abusers without LVH, and control subjects were assessed by ANOVA. Groups were similar concerning age, race, heart rate, resting blood pressure, body surface area, and exercise duration. LVH was present in 16 of 49 (33%) cocaine abusers and three of 30 (10%) control subjects (p=0.02). Of the 16 cocaine abusers with LVH, 10 (63%) had peak exercise blood pressures greater-than-or-equal-to 210 mm Hg, and three others had exercise blood pressures of 200 mm Hg. Therefore, peak exercise systolic blood pressure was significantly higher in cocaine abusers with LVH than in all other groups (p=0.0001). Conclusions. Chronic cocaine abusers with LVH manifest an exaggerated pressor response to treadmill exercise. These data suggest that chronic cocaine abuse predisposes a subset of individuals to a heightened pressor response to a given sympathetic stimulus such as exercise and that this may contribute to the pathogenesis of LVH in chronic cocaine abusers.