Interrelation of coronary calcification, myocardial ischemia, and outcomes in patients with intermediate likelihood of coronary artery disease: a combined positron emission tomography/computed tomography study.

BACKGROUND: Although the value of coronary artery calcium (CAC) for atherosclerosis screening is gaining acceptance, its efficacy in predicting flow-limiting coronary artery disease remains controversial, and its incremental prognostic value over myocardial perfusion is not well established. METHODS AND RESULTS: We evaluated 695 consecutive intermediate-risk patients undergoing combined rest-stress rubidium 82 positron emission tomography (PET) perfusion imaging and CAC scoring on a hybrid PET-computed tomography (CT) scanner. The frequency of abnormal scans among patients with a CAC score > or = 400 was higher than that in patients with a CAC score of 1 to 399 (48.5% versus 21.7%, P<0.001). Multivariate logistic regression supported the concept of a threshold CAC score > or = 400 governing this relationship (odds ratio 2.91, P<0.001); however, the frequency of ischemia among patients with no CAC was 16.0%, and its absence only afforded a negative predictive value of 84.0%. Risk-adjusted survival analysis demonstrated a stepwise increase in event rates (death and myocardial infarction) with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging. Among patients with normal PET myocardial perfusion imaging, the annualized event rate in patients with no CAC was lower than in those with a CAC score > or = 1000 (2.6% versus 12.3%, respectively). Likewise, in patients with ischemia on PET myocardial perfusion imaging, the annualized event rate in those with no CAC was lower than among patients with a CAC score > or = 1000 (8.2% versus 22.1%). CONCLUSIONS: Although increasing CAC content is generally predictive of a higher likelihood of ischemia, its absence does not completely eliminate the possibility of flow-limiting coronary artery disease. Importantly, a stepwise increase occurs in the risk of adverse events with increasing CAC scores in patients with and without ischemia on PET myocardial perfusion imaging.

Transesophageal echocardiography during mitral valve repair underestimates mitral valve area by pressure half-time calculation.

BACKGROUND: Mitral valve repair (MVRr) has become the mainstay of surgical treatment for mitral valvular regurgitation. Evaluation of MVRr by intraoperative transesophageal echocardiography (IOE) has been routinely employed to guide the operation. While the main objective of IOE is to assess for residual mitral regurgitation, it is also important to exclude significant mitral stenosis. Utilisation of pressure half-time (PHT) to estimate mitral valve area (MVA) has been shown to be reliable in normal clinical situations. However, in MVRr, the accuracy of MVA calculation by PHT needs to be ascertained. METHODS AND RESULTS: Data from IOE and post-MVRr transthoracic echocardiography (TTE) from the year 1998 to 2002 were analysed and when required, offline PHT measurements were made. The mean time interval between the two echocardiographic examinations was 10.6 (1 to 56) weeks. In our 36 cases, the IOE MVA was found to be 2.1+/-0.5 cm2, with the corresponding TTE MVA to be 2.7+/-1.0 cm2. MVA by PHT with IOE underestimated TTE findings by 0.6+/-0.9 cm2 (95% CI: -0.85 to -0.24, P=0.001). In 6 patients, the IOE MVA was moderately reduced. Subsequent TTE in these patients showed that the MVA was adequate and was significantly underestimated by IOE in 5 of these patients. In all these cases, IOE underestimated MVA by a margin, which may result in a need to revise the repair. CONCLUSION: We find that IOE immediately after MVRr tends to underestimate MVA by PHT calculation. The underestimation by IOE may have clinical importance in cases when MVA by IOE is moderately reduced. Therefore, pressure half-time measurement should not be used to assess mitral valve areas during mitral valve repair.