Enalapril plus frusemide MAG3 scintigraphy in hypertensive patients with atherosclerosis and moderate renal insufficiency

We performed a retrospective study on 26 patients with moderate renal failu re (mean GFR = 51 +/- 21 ml min(-1) 1.73 m(-2)), hypertension and atheroscl erosis. Apart from three patients who had completely normal renal Doppler u ltrasonography, all patients underwent renal angiography. Three groups of k idneys with different atherosclerotic renal artery involvement were identif ied: Group 1, 24 kidneys with no renal artery stenosis (RAS); Group 2, 18 k idneys with mild (> 25% and < 50% diameter) RAS; and Group 3, 10 kidneys wi th moderate (> 50% diameter) RAS. We used a two-day protocol with frusemide plus enalapril Tc-99(m)-MAG3 scintigraphy. The mean parenchymal transit ti me (MPTT), time to the maximum activity (time to peak) of the renal curve ( T-max), residual activity and split renal uptake were evaluated. The measur ed parameters did not differ before and after enalapril in Group 1 or in Gr oup 2. In Group 3, MPTT and residual activity differed significantly (P < 0 .025) before and after enalapril. The T-max before and after enalapril, MPT T before and after enalapril and residual activity after enalapril differed significantly (P < 0.05) between Groups 1 and 3 and between Groups 2 and 3 . Threshold values were obtained to maximize diagnostic accuracy. The T-max , MPTT and residual activity after enalapril gave satisfactory results, and MPTT performed best with a 75% positive predictive value and a 98% negativ e predictive value for the diagnosis of renal artery stenosis. We conclude that MPTT, measured after enalapril administration, is a useful parameter t o detect renal artery stenosis in patients with hypertension, atheroscleros is and moderate renal insufficiency. ((C) 1998 Lippincott Williams & Wilkin s).