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 venricular 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 tim-activity 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.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)