Effect of Nicorandil on Left Ventricular End-Diastolic Pressure During Exercise in Patients with Hypertrophic Cardiomyopathy

AIMS: Impaired coronary microcirculation is thought to contribute to myocardial ischaemia, causing an abnormal increase in left ventricular end-diastolic pressure during exercise in individuals with hypertrophic cardiomyopathy. The effects of nicorandil on left ventricular end-diastolic pressure during exercise were examined in patients with this condition. METHODS AND RESULTS: Left ventricular pressures and dimensions were measured simultaneously during supine bicycle exercise in 23 patients with nonobstructive hypertrophic cardiomyopathy, before and after intravenous injection of either nicorandil (0.1 mg/kg) or propranolol (0.15 mg/kg). Exercise thallium-201 scintigraphy was also performed. Patients were grouped according to the changes in left ventricular end-diastolic pressure during exercise before treatment. Group I comprised 13 patients in whom left ventricular end-diastolic pressure increased progressively to abnormal values during exercise; group II comprised 10 patients in whom left ventricular end-diastolic pressure changed biphasically. The extents of both left ventricular hypertrophy and ischemic burden during exercise were greater in group I than in group II. Of the eight group I patients who received nicorandil, four individuals exhibited biphasic changes in left ventricular end-diastolic pressure during exercise after its administration whereas four subjects showed no such effect of the drug. Left ventricular end-diastolic pressure increased progressively during exercise after propranolol treatment in all 6 group II patients given this drug. CONCLUSION: Nicorandil has a salutary effect on the changes in left ventricular end-diastolic pressure during exercise in patients with hypertrophic cardiomyopathy.