Detection of coronary artery disease using delayed strain imaging at 5 min after the termination of exercise stress: head to head comparison with conventional treadmill stress echocardiography

BACKGROUND

Prolongation of the time to peak strain (TPS) is a sensitive marker of myocardial ischemia. The purpose of this study was to evaluate whether delayed strain imaging obtained at 5 min after the termination of exercise stress can detect patients with significant coronary artery disease (CAD).

METHODS

A total of 45 patients who underwent treadmill stress echocardiography and coronary angiography were studied. Patients with abnormal wall motion at rest were excluded. Digital echocardiographic images were recorded at baseline and immediately after the termination of treadmill stress. Exercise-induced wall motion abnormality was considered as a marker of myocardial ischemia. Tissue velocity images were also recorded at baseline and 5 min after the termination of treadmill stress, and TPS was measured. TPS ratio was calculated as the ratio between TPS at delayed post-exercise and TPS at baseline.

RESULTS

Coronary angiography revealed that 30 of the 45 patients had significant CAD > or =50% diameter stenosis. The receiver operating characteristics curve demonstrated that cut-off value of TPS ratio 1.10 provides best diagnostic accuracy for vessel-based detection of significant CAD. The sensitivity, specificity, and diagnostic accuracy of the conventional exercise stress echocardiography for detecting patients with CAD were 87%, 80%, and 84%, respectively. The sensitivity, specificity, and accuracy of delayed strain imaging for identifying patients with CAD were 93%, 73%, and 87%, respectively.

CONCLUSION

Delayed strain imaging obtained at 5 min after the termination of exercise stress can accurately detect patients with significant CAD.

Prediction of the response to beta-blocker therapy in patients with dilated cardiomyopathy: comparison of 123I-MIBG scintigraphy and low-dose dobutamine stress echocardiography

BACKGROUND

In this study, we aimed to compare low-dose dobutamine stress echocardiography (DSE) and iodine 123-metaiodobenzylguanidine (MIBG) scintigraphy for predicting the response to beta-blocker therapy in patients with dilated cardiomyopathy (DCM).

METHODS

MIBG imaging was performed in 10 patients with DCM (mean EF 28 ± 8%), who were subsequently treated with beta-blocker therapy. The heart-to-mediastinum (H/M) MIBG uptake ratio was evaluated in initial and delayed images, and the percent washout ratio of myocardial MIBG was determined. DSE was also performed in all patients to measure left ventricular ejection fraction (LVEF) at rest and during dobutamine infusion (10 μg/kg/min). LVEF at rest was also assessed by echocardiography before and after 6 months of beta-blocker therapy.

RESULTS

LVEF was significantly improved after beta-blocker therapy (28 ± 8 to 41 ± 11%, p < 0.001). The relative change in LVEF after beta-blocker therapy was significantly correlated with the relative change in LVEF during DSE (r = 0.68, p < 0.03). The H/M MIBG uptake ratio in both early and delayed imaging was not significantly correlated with the relative change in LVEF in response to beta-blockade therapy.

CONCLUSIONS

The relative change in LVEF during DSE, but not MIBG imaging predicted the relative change in LVEF in response to beta-blockade therapy in a limited number of DCM patients.