Prediction of ischemic events by anatomic M-mode strain rate stress echocardiography

We assessed the prognostic value of anatomic M-mode strain rate stress echocardiography (SRSE) in patients with known or suspected coronary artery disease. Previous studies showing that M-mode SRSE may be an accurate method for detection of coronary artery disease suggest that this technique may be useful for risk stratification.

M-mode SRSE, using a color-coded display of strain rate (SR), was performed in 358 patients (48, dobutamine; 68, bicycle; 242, treadmill). SR was graded by visual assessment of the color-coded display in 12 apical segments. Abnormal rest SR was defined as SR more positive than -1/s (green-yellow). Ischemia was defined by the development of post-systolic shortening or lack of improvement of SR to more negative than -2/s (brown hue) with stress. Patients were followed for cardiac events.

Twelve patients with early intervention for an abnormal two-dimensional stress echocardiogram or stress electrocardiogram were excluded. Follow-up (mean 10.7 months) was completed in 98% (338/346) of the remaining patients. Events occurred in 1.7% (4/230) of patients with normal SRSE compared with 10% (11/108) with abnormal SRSE (P = .002). The annualized hard event (infarction, death) rate in those with normal SRSE was 0.5% versus 7.2% in those with abnormal SRSE (P = .001). Smoking (P = .048, relative risk 2.91), nitrate use (P = .001, relative risk 7.81), and the severity of the abnormality on SRSE (P = .009, relative risk 1.75) independently predicted events. Wall motion assessment was not predictive. Patients with normal SRSE had better event-free survival compared with those with abnormal SRSE (P < .001).

SRSE is an independent predictor of outcome. A normal SRSE predicts a low risk of infarction or death in short-term follow-up.