Effects of sublingual isosorbide dinitrate on left ventricular performance during exercise in patients with myocardial infarction.

In order to investigate left ventricular performance during exercise in patients with myocardial infarction and evaluate the effects of sublingual isosorbide dinitrate (ISDN) on left ventricular performance, we performed a symptom-limited multigraded exercise test using a bicycle ergometer in supine position . Thirty-seven patients with myocardial infarction were evaluated in order to clarify the hemodynamic responses to exercise with and without sublingual ISDN. Patients were subdivided into 3 groups according to the level of pulmonary capillary pressure (PCP) and cardiac index (CI) at peak exercise as follows: Group I (14 patients); PCP < 18 mmHg, CI ≥ 5.0 or CI < 5.0 L/min/m2, Group II (11 patients); PCP ≥ 18 mmHg, CI ≥ 5.0 L/min/m2, Group III (12 patients); PCP ≥ 18 mmHg, CI < 5.0 L/min/m2. Exercise capacity without ISDN (control study) was correlated with left ventricular performance during exercise. Although left ventricular performance in patients who complained of dyspnea or chest pain at peak exercise was worse than those who complained of leg fatigue, we could not predict hemodynamics during exercise from the level of hemodynamic parameters at rest in each patient. Determinant factors of left ventricular performance during exercise were age, previous history of myocardial infarction, the severity of coronary artery lesion and the extent of left ventricular wall motion abnormality which was estimated by left ventriculogram as an index of infarct size. After sublingual ISDN (ISDN study), exercise capacity was improved. No patient terminated exercise because of chest pain and only one did because of dyspnea. While no significant differences in heart rate (HR), mean arterial pressure (MAP) cardiac index (CI), stroke volume index (SVI), left ventricular stroke work index (LVSWI) and systemic vascular resistance (SVR) were observed at peak exercise between the control study and ISDN study in Groups I and II, PCP was lower in the ISDN study than in the control study. On the other hand, CI and LVSWI in Group III increased and SVR significantly decreased at peak exercise. Effects of ISDN on hemodynamics during exercise was well related to the severity of coronary artery lesion and inversely correlated with the infarct size. These results indicate that investigation of hemodynamic response to exercise is a useful method for determination of cardiac rehabilitation program in patients with myocardial infarction and ISDN is an effective drug for the improvement of left ventricular performance during exercise.