Dobutamin-induzierte Veränderungen des myokardialen Blutflusses bei Patienten mit koronarer Herzerkrankung: Eine quantitative Untersuchung mittels [15O] H2O Positronen-Emissions-Tomographie

Abstract

Although dobutamine is currently widely used for stress testing, only little is known about the effects of dobutamine on myocardial blood flow. The purpose of the present study was therefore to analyze quantitatively the regional changes in myocardial blood flow during rest and stress. In order to assess these effects 17 patients (12 men, five women, mean age 57 +/- 8 years) with symptomatic single vessel coronary artery disease (> 70% stenosis) scheduled for coronary angioplasty underwent dobutamine stress testing with a maximum dose of 40 micrograms/kg/min. Myocardial blood flow was measured using 15O H2O position emission tomography at rest and during maximum stress in ischemic and non-ischemic myocardial regions. Dobutamine stress (median dose 30 micrograms/kg/min) increased the rate pressure product significantly (from rest 8697 [95% confidence interval 7959-9435] to stress 16,512 [15,208-17,815] mmHg/min (p < 0.001). Myocardial blood flow during rest was similar in non-ischaemic and ischaemic regions (0.91 [0.93; 0.83-1.28] vs. 1.10 [1.23; 0.91-1.28] ml/min/g, n.s.). During dobutamine stress myocardial blood flow increased in non-ischaemic regions to 2.17 (2.15; 1.77-2.57) ml/min/g, while myocardial blood flow did not increase in ischaemic regions (1.06 [0.97; 0.83-1.28], p < 0.001). Accordingly, dobutamine coronary reserve was 2.42 (2.55; 2.10-2.74) for non-ischaemic regions and 0.98 (1.05; 0.84-1.13) for ischemic regions (p < 0.001). Rate pressure product and myocardial blood flow were significantly correlated (r = 0.79, p < 0.001). A dobutamine-induced increase in rate pressure product was proportional to an increase in myocardial blood flow in non-ischaemic regions. In contrast, myocardial blood flow did not increase in myocardial regions supplied by a severely stenosed coronary artery.