R-PEAK TIME PROLONGATION AND R PEAK DELAY IN LEAD-I, LEAD-V-5, OR LEAD-V-6 - DIAGNOSTIC VALUES AS SIGNS OF MYOCARDIAL DYSFUNCTION IN CHRONIC MITRAL INCOMPETENCE

On the assumption that maximum R peak time prolongation in the left-si ded leads I, V-5, or V-6 and its time relationship to the S peak time of the maximum S amplitude in leads V-1, V-2, or V-3 (representing dor sally directed forces of ventricular depolarization) could indicate th e extent of left ventricular volume overloading and possibly left vent ricular systolic function, these variables and the preoperative findin gs of angiocardiography were compared between patients with chronic mi tral incompetence who, late after corrective valve surgery, had either well-preserved radionuclide left ventricular ejection fraction (group 1, n = 36) or radionuclide left ventricular ejection fraction below 5 0% (group 2, n = 30). Before surgery, group 2 patients had a highly si gnificant lower mean left ventricular ejection fraction, a highly sign ificant greater mean end-systolic volume index, a significantly greate r mean end-diastolic volume index, a significantly greater mean maximu m R peak time in leads I, V-5, or V-6, and a significantly greater pro longation of the maximum R peak time above the S peak time in the righ t precordial leads, as compared with group 1. R peak times greater tha n 50 ms or the presence of R peak delay (maximum R peak time greater t han the S peak time of the maximum right precordial S amplitude) yield s less sensitive but highly reliable results in predicting radionuclid e left ventricular ejection fraction below 50% with both specificity a nd positive predictive values of 100%. Thus, in chronic mitral regurgi tation surgery should not be delayed if patients present these signs b ecause they are specific markers of irreversibly impaired chamber func tion.