Evaluate Effect Of Exercise On Left Ventricular Function In Patients With Slow Coronary Flow By Echocardiography

Objective: Slow coronary flow(SCF)has been reported in patients presenting with normal epicardial coronaries but who show an inappropriate delay in the progression of intracoronary contrast during angiography.This condition,which may affect one or all coronaries.Many of the patients with SCF may experience recurrent acute coronary syndromes,which may increase the incidence of acute myocardial infarction and life-threatening arrhythmias.It has been proposed that it might depend on the presence of inappropriately high resting coronary resistances.Our previous study have found that the left ventricular(LV)systolic and diastolic function in patients with slow coronary flow were decreased at rest.But,The change in LV function with SCF patients during exercise is not yet clear.In this study we evaluated the effect of exercise on LV function in patients with SCF by echocardiography.and discussed the possible mechanism of SCF.Methods: 46 patients(SCF group)with diagnosis of SCF were enrolled in this study.40 age and sex matched adults were included as control group.All subjects have underwent clinical evaluation and exercise stress echocardiography,LV diastolic and systolic functions were assessed by conventional echocardiography,tissue Doppler imaging and two-dimensional speckle tracking echocardiography at rest and during exercise.Results: 1.LV function in patients with SCF at rest:(1)LV systolic function: LV peak systolic longitudinal strain(LS)was lower in patients with SCF than in controls(P < 0.05).There was no difference in LV ejection fraction(LVEF).(2)LV diastolic function: Early diastolic mitral annulus early diastolic velocity(Mitral e')and the ratio between the early mitral inflow velocity and Mitral e'(Mitral E/e')were significantly decreased in the patients with SCF(P< 0.05).2.LV function in patients with SCF during exercise:(1)LVEF,LS and Mitral e? were significant increased in two groups of subjects(P< 0.05).(2)LV systolic function: Compared with the control group,there were no significant difference with respect to LVEF and LS in patients with SCF(P>0.05).(3)LV diastolic function: Compared with the control group,there were no significant difference with Mitral e?,Mitral E/A and Mitral E/e? in patients with SCF(P>0.05).3.The increase in LV function in patients with SCF during exercise: Compared with the control group,?LS and ?Mitral e? were significantly higher in patients with SCF.Conclusion: 1.LV systolic and diastolic function in patients with SCF are impaired at rest.2.LV systolic and diastolic function recover in patients with SCF during exercise,it might relate to the normal reserve capacity and expansion ability of coronary artery.