Safety profile and hemodynamic responses to beta-adrenergic stimulation bydobutamine in heart transplant patients

Study objective: Dobutamine stress echocardiography (DSE) has been used as a screening tool for coronary artery disease after heart transplantation an d in the identification of patients at risk for development of cardiac even ts. However, the safety profile of high-dose dobutamine in heart transplant patients has not been systematically examined. Accordingly, we studied the safety profile and hemodynamic responses to escalating doses of dobutamine to determine the influence of denervation. Design: We assessed the hemodynamic responses, heart rate (HR), and arteria l BP indexes (mean arterial pressure, systolic BP [SBP], diastolic BP [SBP] , and pulse pressure) to dobutamine in 87 heart transplant patients ([mean +/- SD]age, 51 +/- 1 years) and compared the results with 97 nontransplant patients (age, 63.0 +/- 1 years) who served as innervated control subjects, Measurements and results: The baseline HR (84 +/- 2 vs 69 +/- 1 beats/minut e, respectively; p < 0.001) and peak HR response (144 +/- 2 vs 117 +/- 2 be ats/minute, respectively; p < 0.001) were significantly higher in heart tra nsplant patients than in the nontransplant patients. SEP was lower in heart transplant patients than in nontransplant patients at baseline (131 +/- 2 vs 138 +/- 2 mm Hg, respectively; p < 0.02) and at peak (150 +/- 3 vs 158 /- 3 mm Bg, respectively; p < 0.03). However, baseline DBP was higher in tr ansplant patients than in nontransplant patients (86 +/- 1 vs 77 +/- 1 mm H g, respectively; p < 0.001), The decrease in DBP was similar in both groups (15 mm Hg). The dose-response curve for HR was shifted leftward in heart t ransplant patients. Heart transplant patients attained a higher absolute HR at each infusion stage and higher rates of increase, but the decrease in D BP was not significantly different in the two groups, Conclusions: These results show that there is augmented chronotropic respon se and expected decline in DBP in response to dobutamine infusion in heart transplant patients. This increase in myocardial oxygen demand and a decrea se in coronary perfusion pressure may be important mechanisms in the develo pment of ischemic abnormalities that are detectable as regional dysnergy on echocardiography.