THERAPY AND PREVENTION PTCA Asynchronous left ventricular regional function and impaired global diastolic filling in patients with coronary artery

Left ventricular diastolic filling is impaired in many patients with coronary artery disease and normal left ventricular systolic function, and is improved in many patients after coronary angioplasty (PTCA). To investigate the mechanisms for this improvement, we studied regional asynchrony by radionuclide angiography in 26 patients with single-vessel coronary artery disease before and after successful PTCA. Before PTCA, all patients had normal ejection fractions at rest and normal qualitative left ventricular regional wall motion, as determined by radionuclide and contrast angiography. Quantitative left ventricular regional function was assessed by dividing the left ventricular region of interest into 20 sectors. Phase analysis was performed on each sector's time-activity curve, and the average intersector phase difference was used as an index of left ventricular regional synchrony. Before PTCA, average intersector phase difference was increased compared with normal (6.0 ± 2.2 vs 4.0 + 1.7 degrees, p < .005), indicating asynchronous regional function. After PTCA, ejection fraction at rest was unchanged, but peak left ventricular filling rate at rest increased from 2.5 ± 0.6 to 3.0 ± 0.6 end-diastolic volume/sec (p < .001) and was associated with a decrease in average intersector phase difference from 6.0 + 2.2 to 5.1 + 2.3 degrees (p < .05). Average intersector phase difference decreased in 16 of 21 patients in whom peak filling rate increased after PTCA (p < .005), compared with one of five patients in whom peak filling rate was unchanged or decreased. Hence, improved global left ventricular filling after PTCA was associated with more synchronous left ventricular regional behavior. To identify the cause of regional asynchrony before PTCA, we then generated timeactivity curves from each of four left ventricular quadrants. These data indicated that the asynchrony was caused by regional variation in timing of diastolic rather than systolic events and that PTCA resulted in reduction in regional diastolic asynchrony. These data suggest that in many patients with coronary artery disease and normal left ventricular systolic function, impaired global diastolic filling may result from asynchronous left ventricular regional diastolic function, which is a reversible manifestation of myocardial ischemia or reduced coronary flow. Circulation 71, No. 2, 297-307, 1985. DIASTOLIC FILLING of the left ventricle is impaired under resting conditions in many patients with coronary artery disease, including many patients in whom there is no evidence of previous myocardial infarction and in whom left ventricular global and regional left ventricular systolic function is normal.'-' In such patients with stenosis of a single coronary artery, abnormal indexes of left ventricular diastolic filling at rest From the Cardiology Branch, National Heart, Lung, and Blood Institute, and The Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda. Address for correspondence: Robert 0. Bonow, M.D., Bldg. 10, Room 7B-15, NHLBI, National Institutes of Health, Bethesda, MD 20205. Received July 16, 1984; revision accepted Nov. 15, 1984. improve after successful percutaneous transluminal coronary angioplasty (PTCA), suggesting that impaired diastolic filling at rest may be a reversible manifestation of regional myocardial ischemia or reduced regional coronary flow.8 It is possible that in patients with coronary artery disease regional differences in myocardial blood flow result in regional alterations in either the magnitude or the temporal synchrony of contraction or relaxation and that regional asynchrony contributes to impaired global ventricular filling. 1 2 7, 9-12 If this is the case, improved global diastolic filling after successful PTCA, or other interventions that restore coronary flow, may result from an improvement in regional left ventricular asynchrony. In Vol. 71, No. 2, February 1985 297 by gest on July 5, 2017 http://ciajournals.org/ D ow nladed from