Assessment of the myocardial area at risk: comparing T2-weighted cardiovascular magnetic resonance imaging with contrast-enhanced cine (CE-SSFP) imaging-a DANAMI3 substudy.

AIMS: Myocardial salvage following treatment for ST-segment elevation myocardial infarction is prognostic for morbidity and mortality. Studies with myocardial salvage as endpoint rely on valid assessment of the myocardial area at risk (AAR). T2-weighted cardiovascular magnetic resonance (CMR) imaging is the preferred method to assess the AAR. However, T2-weighted imaging can be of poor image quality and uninterpretable. Contrast-enhanced (CE) cine imaging can also show AAR and our aim was to investigate if CE-cine can replace T2-weighted imaging. Cine imaging is part of a standard CMR-protocol and implementing CE-cine imaging for assessment of the AAR would mean shorter investigation time. METHODS AND RESULTS: As a DANAMI-3 substudy, we performed successful dual imaging of the AAR in 166 participants using both T2-weighted short tau inversion recovery (T2-STIR) and CE-cine imaging. T2-STIR imaging was non-diagnostic in nine and CE-cine in one scan during the period. CE-cine measured 4.7% of left ventricle (LV) [95% confidence interval 3.2-6.2%] smaller AAR compared with T2-STIR images (P < 0.001). Visual analysis of a plot of infarct size vs. AAR showed an overestimation of the AAR when measured with T2-STIR images. There was no difference in AAR with CE-cine in an interobserver analysis of 46 scans [1.2 g (standard deviation 9.5), P = 0.42]. CONCLUSIONS: CE-cine imaging shows good internal consistency in assessment of the AAR. A visual inspection reveals possible overestimation of AAR with T2-STIR images. There is good interobserver agreement in the analysis of CE-cine imaging. CE-cine can replace T2-STIR imaging resulting in a more valid assessment of the myocardial AAR.

Transthoracic Doppler echocardiography compared with positron emission tomography for assessment of coronary microvascular dysfunction: The iPOWER study.

BACKGROUND: Coronary microvascular function can be assessed by transthoracic Doppler echocardiography as a coronary flow velocity reserve (TTDE CFVR) and by positron emission tomography as a myocardial blood flow reserve (PET MBFR). PET MBFR is regarded the noninvasive reference standard for measuring coronary microvascular function but has limited availability. We compared TTDE CFVR with PET MBFR in women with angina pectoris and no obstructive coronary artery disease and assessed repeatability of TTDE CFVR. METHODS: From a cohort of women with angina and no obstructive coronary artery stenosis at invasive coronary angiography, TTDE CFVR by dipyridamole induced stress and MBFR by rubidium-82 PET with adenosine was successfully measured in 107 subjects. Repeatability of TTDE CFVR was assessed in 10 symptomatic women and in 10 healthy individuals. RESULTS: MBFR was systematically higher than CFVR. Median MBFR (interquartile range, IQR) was 2.68 (2.29-3.10) and CFVR (IQR) was 2.31 (1.89-2.72). Pearson's correlation coefficient was 0.36 (p<0.01). Limits of agreement (2·standard deviation) assessed by the Bland-Altman (confidence interval, CI) method was 1.49 (1.29;1.69) and unaffected by time-interval between examinations. Results were similar when adjusting for rate pressure product or focusing on perfusion of the left anterior descending artery region. Limits of agreement (CI) for repeated CFVR in 10 healthy individuals and in 10 women with angina was 0.44 (0.21;0.68) and 0.48 (0.22; 0.74), respectively. CONCLUSION: CFVR had a good repeatability, but the agreement between CFVR and MBFR was modest. Divergence could be due to methodology differences; TTDE estimates flow velocities whereas PET estimates myocardial blood flow.