Characterizing stenosis severity of coronary heart disease by myocardial work measurement in patients with preserved ejection fraction.

BACKGROUND

The novel echocardiographic parameter of myocardial work incorporates left ventricular pressure into the assessment of left ventricular systolic function and thereby corrects for afterload. We sought to investigate the diagnostic value of myocardial work to identify different grades of stenosis severity in coronary heart disease (CHD) patients with preserved left ventricular ejection fraction and without regional wall motion abnormalities.

METHODS

One hundred and seventeen consecutive subjects with preserved ejection fraction referred for coronary angiography were randomized and prospectively included in this study. Forty-six in the control group, and 25, 24, and 22 in each of the grade-1, grade-2, and grade-3 CHD groups as classified by the Gensini score. The following indices of myocardial work were assessed with a Vivid E95 Version 203 instrument: global work index (GWI), global constructive work (GCW), global wasted work (GWW), global work efficiency (GWE).

RESULTS

Both GWI (P<0.001) and GCW (P<0.001) decreased significantly in CHD grade-1, increased slightly in CHD grade-2 compared with CHD grade-1, and decreased significantly in CHD grade-3. GWW (P<0.001) increased significantly from CHD grade-1 to CHD grade-3, while GWE (P<0.001) decreased significantly from CHD grade-1 to CHD grade-3. Receiver operating characteristic curves analysis revealed good discrimination between the control group and CHD grade-3 for GWI [area under the curve (AUC): 0.810; 95% confidence interval (CI): 0.691-0.930], GCW (AUC: 0.758; 95% CI: 0.631-0.885), GWW (AUC: 0.754; 95% CI: 0.624-0.885) and GWE (AUC: 0.817; 95% CI: 0.709-0.926). The assessment of intraobserver and interobserver variability in the MW echocardiographic data documented good interclass correlation coefficients (all >0.85).

CONCLUSIONS

Myocardial work incorporates left ventricular pressure into the assessment of left ventricular systolic function and thereby corrects for afterload. It identifies patients with incipient left ventricular dysfunction caused by chronic ischemia due to CHD. A gradual worsening of myocardial work parameters was observed when comparing patients with higher degrees of stenosis severity. Therefore, adding myocardial work when evaluating patients with suspected CHD may help increase diagnostic accuracy.