Persistent reduction in left ventricular asynergy in patients with acute myocardial infarction by intravenous infusion of nitroglycerin.

Abstract

Intravenous nitroglycerin (NG) infusion in patients with acute myocardial infarction (AMI) has been shown to improve left ventricular function and myocardial perfusion and to decrease ischemic injury and creatine kinase (CK) indexes of infarct size. To determine whether early NG infusions in patients with AMI decreases the extent of left ventricular asynergy, we used two-dimensional echocardiography to measure asynergic segments (akinesis and/or dyskinesis) at four serial short-axis levels from base to apex (mitral, M; chordal, C; midpapillary, MP; low papillary, LP) in 22 patients with a first anterior AMI. Patients were randomized between infusions of NG (n = 11) or 5% dextrose in water (controls, n = 11) within 5.6 hr after the onset of pain. NG infusion rates were titrated to lower mean arterial pressure to an average level of 7% below control (but not below 80 mm Hg) and were maintained at this level for the duration of the infusions (39 hr). After NG, left ventricular function improved as left ventricular filling pressure decreased (p less than .005), and sigma ST on precordial ST segment mapping decreased (p less than .001). These parameters did not change in control subjects. Computed CK infarct size was smaller in the NG group than in the control group (p less than .05). Before the infusions, the mean extent of left ventricular asynergy (% left ventricular circumference) were similar in both groups: M, 18% vs 21%; C, 22% vs 23%; MP, 26% vs 24%; LP, 32% vs 29%. In addition, the computed total left ventricular asynergy (% surface area) was also similar for these two groups before therapy (25% vs 25%). There was no change in left ventricular asynergy from pretreatment values by 1 hr and 10 days among control subjects: M, 18% vs 18% vs 17%; C, 22% vs 22%; MP, 26% vs 26% vs 22%; LP, 32% vs 33% vs 33%; total 25% vs 25% vs 24% (multiple measures analysis of variance). In contrast, there was a significant decrease (p less than .001) in left ventricular asynergy from pretreatment values by 1 hr and 10 days with NG: M, 21% vs 10% vs 8%; C, 23% vs 12% vs 10%; MP, 24% vs 13% vs 9%; LP, 29% vs 14% vs 10%; total, 25% vs 12% vs 9%.(ABSTRACT TRUNCATED AT 400 WORDS)