Detection of Myocardial Injury by CMR After Transcatheter Aortic Valve Replacement
What is the incidence and degree of ischemic myocardial damage using cardiac magnetic resonance imaging (CMR) and myocardial biomarkers in patients undergoing transcatheter aortic valve replacement (TAVR)?
Patients with severe aortic stenosis (n = 61) underwent CMR before and after TAVR for the assessment of new myocardial injury. High-sensitivity cardiac troponin T (hs-cTNT) and creatine kinase-myocardial band were measured before and at 24, 48, and 72 hours after TAVR. The receiver operating characteristic curve was analyzed for discrimination of new myocardial infarctions (MIs) with biomarkers; the threshold for hs-cTnT was calculated using the Youden index.
After TAVR, new myocardial late enhancement (LE) with an ischemic pattern occurred in 11 patients (18%), with a mean mass of 3.7 g (interquartile range, 1.2-6 g) or 1.8% (interquartile range, 1.3%-4.1%) of the left ventricular mass. Patients with new LE had a decreased left ventricular function (ejection fraction: pre, 55.5 ± 14.1% vs. post, 45.3 ± 14.9%; p = 0.001). In patients without new LE, no differences were observed (ejection fraction: pre, 53.9 ± 17.3% vs. post, 54.6 ± 16.3%; p = NS) after TAVR.
The authors concluded that new ischemic-type myocardial LE after TAVR can be observed in a notable proportion of patients and is assumed to be of embolic origin.
The study reports that new ischemic-type hyperenhancement detected by CMR occurs in a notable proportion of patients undergoing TAVR. The small size, subendocardial or intramural localization, and multifocal distribution of the lesions are findings that suggest an embolic origin. It appears that myocardial injury detected by CMR may be caused by embolism related to catheter manipulations in patients undergoing TAVR, and additional research is needed to confirm this mechanism and to develop improved valve prostheses, delivery systems with protective features, and myocardial protection strategies.
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