Microalbuminuria is a marker of left ventricular hypertrophy but not hyperinsulinemia in nondiabetic atherosclerotic patients

Abstract

Microalbuminuria predicts cardiovascular events in diabetic and nondiabetic patients. For a better understanding of the physiopathological importance of microalbuminuria in atherosclerotic disease, we evaluated the relation between urinary albumin excretion and arterial blood pressure, left ventricular mass, insulin, and lipid levels. The studies were conducted in patients with atherosclerotic peripheral vascular disease. Urinary albumin excretion (studied by nephelometry; an average of triplicate collections from 8 PM to 8 AM), casual blood pressure, echocardiographic left ventricular mass index and wall thickness, plasma immunoreactive insulin and C-peptide (both basally and after a 75-g oral glucose load), blood lipids, and fibrinogen were studied in eight normal subjects and 20 nonobese, nondiabetic male patients with angiographically documented atherosclerotic peripheral vascular disease and preserved renal function, 12 of whom were either hypertensive or on antihypertensive treatment. Eight patients were microalbuminuric (urinary albumin >20 μg/min) and 12 were not. Ankle-arm index and calf and foot transcutaneous oxygen tension were reduced in comparison with normal control subjects but superim-posable between the two patient groups to indicate a comparable clinical progression of the vascular disease. In the microalbuminuric subjects, left ventricular mass index was greater, interventricular . septum was thicker, and cardiac hypertrophy was more frequent than in nonmicroalbuminuric patients. The prevalence of hypertension tended to be greater and systolic blood pressure values were higher in the presence of microalbuminuria. Overall, a highly significant relation existed between urinary albumin excretion and left ventricular mass. Systolic blood pressure was greater and a history of arterial hypertension was more frequent among microalbuminurics, whereas diastolic blood pressure values showed a statistically significant correlation with both variables. No difference in postload blood glucose and basal and stimulated insulin and C-peptide existed between the two groups of patients. Plasma lipids and fibrinogen did not differ significantly. Urinary albumin excretion was mainly a covariate of left ventricular mass values in these nondiabetic patients with macrovascular disease, but the data do not support previous suggestions of microalbuminuria as a marker of either widespread atherosclerosis as such or insulin resistance. The association between microalbuminuria and cardiac hypertrophy can be explained by coexistent arterial hypertension, an abnormality widely prevalent in atherosclerotic patients, although the limits of conventional blood pressure measurements as an index of daily pressor load tend to mask it. The underlying presence of a major risk factor such as cardiac hypertrophy might explain the previously reported predictive power of microalbuminuria for cardiac events.