Myocardial contrast echocardiography for distinguishing ischemic from nonischemic first-onset acute heart failure - Insights into the mechanism of acute heart failure

Background - Distinguishing ischemic from nonischemic origin in patients presenting with acute heart failure (AHF) not resulting from acute myocardial infarction has both therapeutic and prognostic implications. The aim of the study was to assess whether myocardial contrast echocardiography (MCE) can identify underlying coronary artery disease ( CAD) as the cause of AHF. Methods and Results - Fifty-two consecutive patients with AHF with no prior clinical history of CAD and no clinical evidence of acute myocardial infarction underwent resting echocardiography and MCE both at rest and after dipyridamole stress at a mean of 9 +/- 2 days after admission. All patients underwent coronary arteriography before discharge. Of the 52 patients, 22 demonstrated flow-limiting CAD (> 50% luminal diameter narrowing). Sensitivity, specificity, and positive and negative predictive values of MCE for the detection of CAD were 82%, 97%, 95%, and 88%, respectively. Among clinical, ECG, biochemical, resting echocardiographic, and MCE markers of CAD, MCE was the only independent predictor of CAD (P < 0.0001). Quantitative MCE demonstrated significantly (P < 0.0001) lower myocardial blood flow velocity reserve in vascular territories subtended by > 50% CAD (0.59 +/- 0.46) compared with patients with normal coronary arteries (1.99 +/- 1.00). However, myocardial blood flow velocity reserve in patients with no significant CAD was significantly (P = 0.03) lower compared with control (2.91 +/- 0.41). Myocardial blood flow velocity reserve correlated significantly (P < 0.0001) with increasing severity of CAD. Conclusions - MCE, which is a bedside technique, may be used to detect CAD in patients presenting with AHF without a prior history of CAD or evidence of acute myocardial infarction. Quantitative MCE may further risk-stratify patients with AHF but no CAD.