Regional diagnosis in patients with unstable and stable angina pectoris: Nicorandil stress myocardial contrast echocardiography and magnetic resonance imaging

Abstract

Background: Regional diagnostic imaging in patients with unstable angina is a challenge for cardiologists. To determine whether or not nicorandil, a hybrid compound of KATP channel opener and nitrate, stress myocardial contrast echocardiography (MCE) and magnetic resonance imaging (MRI) are clinically useful in prediction of critical coronary arterial stenosis in angina pectoris (AP) including unstable AP, we conducted a prospective study. Methods: Consecutive 101 patients with AP including unstable AP (n=50) without a history of ST elevation, previous myocardial infarction and coronary bypass surgery were enrolled. All the patients underwent nicorandil stress MCE and MRI. MCE was performed with gray scale ultra-harmonic mode (1.3 MHz/3.6 MHz) under maximum mechanical index during intravenous drip infusion of Levovist during rest and nicorandil stress (0.1 mg/kg iv). End-systolic triggering images (triggering interval of 1, 2, 3 and 4 beats) were recorded. Gadolinium-enhanced MRI was acquired at late-systolic phase during rest and nicorandil stress. Each myocardial region (left anterior descending artery, left circumflex artery, right coronary artery) imaged by MCE and MRI was evaluated before coronary arteriography (CAG) by two independent reviewers who were blinded to the clinical data. All the patients underwent quantitative CAG within five days after MCE and MRI. Results: There was no adverse effects or angina during nicorandil stress MCE in any patients. Prediction rate by the nicorandil stress MCE (303 regions) and MRI of critical stenosis (70% in QCA) were 79% and 89% in sensitivity, 96% and 96% in specificity, and 91% and 93% in accuracy, respectively. In a subgroup of multivessel disease (n=26), sensitivity, specificity and accuracy by MCE were 86%, 94%, and 88%, respectively. Conclusion: Nicorandil stress MCE and MRI are safe, useful and economical noninvasive techniques to assess myocardial regional perfusion in patients with AP including unstable AP, especially associated with multivessel lesions.