MR predicts cardiomyopathy recovery
Findings from cardiac MR (CMR) and a novel biomarker better predict left ventricular reverse remodeling (LVRR) in patients with recent-onset dilated cardiomyopathy than do endomyocardial biopsy results, according to a study published Jan. 8 in the Journal of the American College of Cardiology: Heart Failure. While the study had many limitations, it underscores the value of CMR, the accompanying editorial suggested.
Milos Kubanek, MD, PhD, of the cardiology department at the Institute for Clinical and Experimental Medicine in Prague, and colleagues pointed out that LVRR is associated with a favorable prognosis in patients with dilated cardiomyopathy but little is known about LVRR prediction in practice. “CMR that visualizes the extent of myocardial damage and myocardial edema in individuals with myocarditis could provide new insights into the process of LVRR,” they wrote. “In addition, novel biomarkers, such as high-sensitivity cardiac troponin T, B-type natriuretic peptide (BNP) and galectin-3, could elucidate mechanisms of LVRR and/or predict this event because they are closely associated with myocyte necrosis, myocardial wall stress and remodeling, as well as with the prognosis.”
The researchers enrolled 44 consecutive patients with a history of symptoms less than six months who were admitted to a hospital between 2008 and 2010. Each patient received a baseline clinical assessment, electrocardiography, echocardiography, cardiopulmonary exercise testing, CMR and endomyocardial biopsy. The morning before endomyocardial biopsy patients also provided a blood sample for biomarker analyses. At three-, six- and 12-month follow-up, patients underwent clinical evaluation, electrocardiography, echocardiography, cardiopulmonary exercise testing, biochemical analysis and BNP measurement. CMR was performed at study completion at 12 months.
They defined LVRR as an absolute increase in left ventricular ejection fraction of 10 percent or greater and a final value of greater than 35 percent with a decrease in left ventricular end-diastolic dimension of 10 percent or greater at 12-month follow-up. Thirty-nine patients completed the 12-month follow-up and 20 achieved LVRR.
An analysis by Kubanek et al found two independent predictors at baseline: lower extent of late gadolinium enhancement and higher myocardial edema ratio measured by CMR, with a sensitivity of 70 percent and a specificity of 78 percent. The latest BNP plasma level was the strongest predictor of LVRR at three months, with a level of less than 344 ng/l predicted LVRR having a sensitivity of 95 percent and specificity of 50 percent. CMR findings were stronger than endomyocardial biopsy results, biomarker values and conventional methods and the latest BNP plasma was the strongest predictor at three months.
“[O]ur study revealed novel predictors of LVRR with an acceptable predictive capacity, namely, variables derived from CMR and serial BNP testing. In addition, we evaluated the predictors of LVRR, not only at baseline, but also longitudinally,” they wrote. “As a result, we could identify specific cutoff points for each follow-up period and showed that the novel predictors provided an earlier prediction of LVRR than the conventional methods.”
Kubanek and colleagues suggested that the ability to identify patients with dilated cardiomyopathy likely to achieve LVRR might help physicians in the use of implantable cardioverter-defibrillators or in optimal timing of transplantation referral. They recommended including CMR in the baseline assessment of patients with recent-onset dilated cardiomyopathy and BNP measurement at three months.
Matthias G. Friedrich, MD, of the Montreal Heart Institute in Canada, wrote in an editorial that the study was small; the selection process may have missed some types of patients; the results may apply to only patients with suspected chronic inflammation at biopsy; and the protocol didn’t reflect real-life practice in which a reader would look at edema and the extent of injury together and not separately, which might improve CMR’s predictive value. But he emphasized that the results spotlight CMR’s diagnostic and predictive value.
“There is little doubt that in patients with recent-onset cardiomyopathy, as in other acute myocardial diseases, functional recovery can generally be predicted by a single CMR scan if done at the time of clinical presentation,” Friedrich wrote, adding that studies with larger samples sizes were needed. “If these results can be confirmed, the prediction of the future, at least in acute myocardial disease, may not be that difficult after all.”