Determination of ejection fraction by echocardiography in patients treated with P.E.T.N

The purpose of this single-blind study carried out on 20 patients was to assess the effects of a long-acting nitrate derivative on the stroke index, which reflects left ventricular function. Following a 4 weeks' period of observation without any treatment (except for sublingual nitroglycerin during anginal attacks), an echocardiographic study of the left ventricle was performed. The distance between the endocardium lining the interventricular septum and that lining the posterior wall of the left ventricle was measured at the end of the diastole (R wave of the ECG) and at the end of the systole (shortest measurable distance). The rule of cubes was used to determine the ventricular volume and to calculate the stroke index. The patients then received pentaerythritol tetranitrate in daily doses of 240 mg for 30 consecutive days, after which a new echocardiographic study was done and the stroke index calculated again. The improvement in stroke index was more than three times the standard deviation before treatment in 15 patients (75%) and even six times greater in 8 of these (40%). No improvement was observed in the remaining 5 patients. In the group as a whole the stroke index increased from 0.418 +/- 0.135 to 0.504 +/- 0.115.