Myocardial Function Index Predicts Mortality in Amyloid Light Chain Cardiomyopathy

In patients with light chain amyloidosis (AL), cardiovascular disease persists as the leading cause of morbidity and mortality. At present, in patients with AL cardiomyopathy, prognostic evaluation primarily depends on distinct proxy measurements to estimate and calculate mortality. In light of detected myocardial systolic and diastolic volume variations, Nadia Akhiyat, MD, of the Mayo Clinic, in Rochester, MN, and colleagues described a single cardiac-magnetic resonance imaging (MRI)-derived measurement (CMR) to assess AL cardiomyopathy mortality.

The team reviewed data collected from 1997 to 2001 of 129 consecutive AL cardiomyopathy patients, who underwent CMR. Volume change of the myocardium at end systole and end diastole was evaluated with CMR. To calculate myocardial function index (MFI), researchers used operator tracings to combine blood pool and myocardial volume measures as confluent elements of myocardial function. Using adjusted hazard ratios (HRs) derived by a Cox model, MFI and death association was evaluated.

Sixty-eight percent of the participants were women, and the mean age was approximately 60 years. From CMR (at which time data were reviewed) median survival was 47 months. Assessed by echocardiography, mean left ventricular ejection fraction was 55% ± 12 and mean calculated MFI was 19.8% ± 7. MFI is strongly associated with death (HR, 0.004; 95% confidence interval [CI], 0.00002-0.0838; P = .0003). The strong predictive value of MFI when controlled for age (HR, 0.006; 95% CI, 0.00003-0.1156; P = .0006) was confirmed via a multivariate analysis.

The authors concluded that in AL cardiomyopathy, mortality strongly associates with MFI. Contrasting with previous assessments of ventricular function (based on extracellular volume imaging, myocardial perfusion imaging, and myocardial contraction fraction), MFI was easily derived from CMR and takes into account myocardial volumes and blood pool as intrinsic components of myocardial function. Additional studies should be conducted to assess MFI among patients with heart failure of varying etiology.

Reference

Akhiyat NS, Anand V, Ryu A, et al. Myocardial function index predicts mortality in amyloid light chain cardiomyopathy. Presented at: American Heart Association Scientific Sessions 2020; November 13-20, 2020. Abstract P1809.

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