Abstract
IntroductionLeft main coronary artery(LMCA) disease is prognostically the most important lesion in the coronary tree. LMCA differs from the other coronaries in having high elastin content. As aortic blood pressure (BP) directly affects the heart and emerged as independent predictor of major cardiovascular events, there is heightened interest in exploring its relationship with coronary artery disease (CAD). Aortic pulsatility (AP) measurement eliminates the effect of cardiac output and vascular resistance and is shown to be an independent predictor of cardiovascular events in CAD.HypothesisAs the left main is an elastic vessel, we hypothesized that pulsatile stress may be an independent determinant of disease in this artery.MethodsThis was a prospective cohort study in patients undergoing coronary angiography for suspected CAD between the years 2011 and 2016(n=4633, 25% female) at King Abdul Aziz Cardiac Center, Riyadh, Saudi Arabia. We excluded patients with acute myocardial infarction, cardiogenic shock and significant valvular heart disease. Aortic systolic and diastolic BP were measured in the ascending aorta. MAP was obtained by direct integration of the BP curve. PP was calculated as the difference between systolic and diastolic BP. AP was calculated as PP divided by MAP. CAD was defined as > 50% stenosis in LMCA and the 3 major coronaries (left anterior descending, circumflex and right coronary artery). The AP in patients with LMCA disease was compared to those with non-obstructive, 1, 2 and 3-vd as well with LMCA and 3-vd.ResultsSix percent of the study population had LMCA disease (mean age 60±11 years, 25% female). LMCA disease was associated with higher PP (69±22 vs. 58±18, p<0.0001) despite similar MAP (94±16 vs. 94.5±14, p=0.92) compared with non-LMCA disease. AP was significantly higher (0.72±0.30) in LMCA disease compared with; 3-vd( 0.63±0.32); 2-vd(0.61±0.28), 1-vd(0.58±0.31) and non-obstructive CAD (0.52±0.26) (p<0.0001). In a stepwise regression model, AP was an independent predictor of LMCA disease( R=0.68,P<0.0001) when adjusted for potential confounders, including MAP, age and gender.ConclusionsWe conclude that LMCA disease is independently associated with high aortic pulsatility compared with disease of other coronary vessels,including 3-vd. Considering aortic pulsatile stress to be an independent cardiovascular prognosticator, stiffness of the LMCA may play an important role in plaque formation, hitherto ignored. More research is warranted to test our proof-of-concept study, including outcome.