Improved left ventricular function and topography by prolonged nitroglycerin therapy after acute myocardial infarction.

To determine whether decreasing preload and afterload by prolonged nitroglycerin therapy (NTG) after acute myocardial infarction (AMI) might improve left ventricular (LV) geometry and function, 43 patients with a first anterior transmural AMI (ATAMI) were given low-dose intravenous NTG infusion for the first 48 h and then randomized to buccal NTG (1-3 mg t.i.d., five hourly with an eight-h washout period to avoid vascular tolerance; dose titrated as for i.v. NTG for 10% decrease in blood pressure but not below 80 mm Hg) or placebo for six weeks. All patients had serial two-dimensional echocardiography for 12 weeks for regional LV function and topography: Expansion index = asynergic/non-asynergic endocardial segment length; Thinning ratio = asynergic/normal wall thickness. Asynergy was defined as akinesis + dyskinesis. Between initial and 12-week studies, expansion index did not change in the buccal NTG group (2.09 vs 2.28, N.S.; n = 23) but increased in the placebo group (2.10 vs 2.89, p less than 0.05; n = 20). Over the same period, thinning ratio was unchanged with buccal NTG (0.82 vs 0.77, N.S.) but increased with placebo (0.78 vs 0.66 p less than 0.05). Both expansion and thinning at 12 weeks were greater with placebo than buccal NTG (p less than 0.01). The results indicate that prolonged NTG therapy decreased infarct expansion and infarct thinning. Compared to placebo, the NTG group also showed improved hemodynamics, decreased LV volume and asynergy, and increased ejection fraction. Thus, prolonged NTG therapy after ATAMI preserves LV function and topography. The beneficial early and late remodeling with prolonged NTG therapy might prevent aneurysm formation.