Radionuclide assessment of right ventricular contractile reserve after acute myocardial infarction.
Conflicting data have been reported about the implications of a decreased right ventricular (RV) contractile reserve (i.e., a < 5% stress-induced increase in ejection fraction [EF]). If a reduced reserve corresponds to ischemia, it will probably be associated with an electrocardiographic marker of RV ischemia, stress-induced ST-segment elevation (increases ST) in leads V3R to V6R. To test this hypothesis, 98 asymptomatic postinfarction patients (27 with RV infarction) were assigned to a dobutamine stress test (maximal dose 40 micrograms/kg/min) with equilibrium radionuclide angiography and electrocardiographic study, including leads V3R to V6R. All but 11 patients underwent coronary angiography. A dobutamine-induced increases ST in VR leads was seen in 24 patients with and in 8 without RV infarction. This electrocardiographic sign was 75% sensitive and 84% specific for the diagnosis of proximal right coronary artery disease. It was 61% sensitive and 74% specific for the detection of reduced RV contractile reserve. Patients with RV infarction had reduced RVEF at rest (38 +/- 9%), but the mean contractile reserve was normal (12 +/- 12%). The contractile reserve was significantly smaller in patients with proximal versus distal or no right coronary artery disease. It was also smaller (P < 0.01) in patients with increased ST versus no increased ST. In conclusion, high doses of dobutamine are useful in assessing RV contractile reserve after acute myocardial infarction. In these patients, a reduced RV contractile reserve is related to proximal right coronary artery disease and is associated with stress-induced increased ST in VR leads.
Coma-Canella
I
I
Coronary Care Unit, La Paz Hospital, Madrid, Spain.
del Val Gómez Martínez
M
M
Terol
I
I
Gallardo
F
F
Castro Beiras
J M
JM
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D017023:Coronary Angiography; D004280:Dobutamine; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011877:Radionuclide Imaging; D013318:Stroke Volume / Q000502:physiology; D016278:Ventricular Function, Right / Q000187:drug effects / Q000502:physiology*
D004280:Dobutamine