P463Diagnostic value of exercise-induced post-ischemic left ventricular diastolic stunning in patients with intermediate coronary lesions: comparison with myocardial fractional flow reserve

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Background: Quantitative analysis of prolonged regional left ventricular (LV) diastolic dysfunction or diastolic stunning has provided a more sensitive estimation of the myocardial ischemia. The aim of this study is to evaluate the diagnostic value of diastolic stunning detected by 2D speckle-tracking strain imaging (SI) compared with the invasively assessed myocardial fractional flow reserve (FFR) in patients with intermediate coronary lesion.Methods: Sixty-five consecutive patients (12 females, mean 66.8 yrs) who had a stenosis of moderate severity in one major coronary artery were recruited. Treadmill exercise echocardiography (TME) with SI study by using a ultrasound system (Atrida; Toshiba Medical Systems), and coronary arteriography with FFR measurements were performed. Patients with abnormal results on TME had stress-induced regional wall motion abnormalities. In SI study, transverse strain images were obtained in each segment at rest and 5 min after treadmill exercise. The end systolic values of strain at the closure of the aortic valve (A) and at the one-third point of diastole duration (B) were measured. The strain imaging diastolic index (SI-DI) was determined as (A × B)/A × 100%, and the ratio of SI-DI before and after exercise (SI-DI ratio) was used to identify regional LV delayed relaxation. A positive SI study was defined as SI-DI ratio ≤ 0.74.Results: The FFR at maximum hyperemia averaged 0.79 ± 0.10 and quantitative angiography averaged 49.0 ± 10.4%. Receiver-operator characteristic analysis of FFR by TME was 0.78, which yielded a sensitivity and specificity of 95% and 100%, respectively. The best cutoff value of the FFR by SI study yielded optimal cutoff values of 0.83. Sensitivity and specificity of the FFR were 100% and 95%, respectively. During follow-up period, the CCS functional class of the patients with FFR ≥0.83 had improved from 2.4 to 1.1 (p <0.05). However, the patients with FFR of 0.76 to 0.82 had not improved, from 2.8 to 2.3 (p = 0.13), and 18 patients (82%) underwent coronary intervention.Conclusions: The detection of LV diastolic stunning by using SI may improve the relation between the inducible myocardial ischemia and FFR measurement, and FFR <0.83 according to SI study could be the best cut-off point to predict cardiac events.

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