Significance of nitroglycerin-induced hypotension with inferior wall acute myocardial infarction

Up to 60% of patients with inferior wall acute myocardial infarction (AMI) develop hypotension. In many cases, profound hypotension is precipitated by the administration of nitroglycerin. To test the hypothesis that this hypotensive response to nitroglycerin may be related to right ventricular (RV) involvement, we compared 20 patients with electrocardiographic and enzyme-documented inferior wall AMI and marked hypotension (greater than 30 mm Hg decrease in systolic blood pressure, with symptoms) after nitrate administration, to 20 patients with documented inferior AMI, but without hypotension after administration of nitroglycerin. The presence of RV involvement was determined by electrocardiographic criteria of 1 mm of ST-segment elevation in at least 2 right precordial chest leads. Fifteen of the 20 patients who demonstrated a marked hypotensive response to nitroglycerin had evidence of RV involvement, while in 18 of the 20 patients without hypotension after nitrates there was no evidence of RV involvement. In a separate analysis of 28 patients with documented RV involvement in an inferior AMI, 20 developed hypotension in response to nitrates. Thus, in the setting of an inferior AMI, a marked hypotensive response to nitrates suggests the presence of RV involvement. Moreover, hypotension after nitrate administration may be anticipated in patients with known RV infarction, and in such patients, nitrates should be administered carefully.