CMR vs Endomyocardial Biopsy to Diagnose Cardiac Amyloidosis

Noninvasive cardiovascular magnetic resonance (CMR) was found to have excellent diagnostic accuracy for cardiac amyloidosis, according to a study published in Clinical Research in Cardiology.

In this multicenter study, the diagnostic values of CMR vs endomyocardial biopsy (EMB) for cardiac amyloidosis were compared. A total of 160 patients with symptoms of heart failure and presence of left ventricular (LV) hypertrophy of unknown origin who presented to a specialized cardiomyopathy center in Germany were enrolled. Study participants underwent CMR and EMB, as well as additional subtyping based on EMB specimens and monoclonal protein studies in cases of cardiac amyloidosis diagnosis.

An EMB-based diagnosis of cardiac amyloidosis was made in 120 patients (cardiac amyloidosis group; median age, 75 years; 83% men), and 40 patients had other diagnoses (control group; median age, 52 years; 78% men). In the cardiac amyloidosis group, 114 patients (95%) had a characteristic pattern of late-gadolinium enhancement (LGE) that was indicative of cardiac amyloidosis. Within the control group, 1 patient (2%) had a false-positive LGE pattern that was suggestive of cardiac amyloidosis.

None of the patients in the cardiac amyloidosis group had increased T1/extracellular volume levels without a characteristic pattern of LGE indicative of cardiac amyloidosis. LGE-CMR had a 95% sensitivity and a 98% specificity for cardiac amyloidosis diagnosis.

The combination of an LGE pattern indicative of cardiac amyloidosis with unremarkable monoclonal protein studies led to a diagnosis of transthyretin amyloidosis–cardiac amyloidosis (which was confirmed by EMB), and had a 98% specificity (95% CI, 92%-100%) and a positive predictive value of 99% (95% CI, 92%-100%). The EMB-associated risk for complications was 3.13%, with no detrimental or persistent complications.

The study authors noted that their cohort does not reflect an “unselected” cardiology population of patients and includes only those with symptoms of heart failure in the presence of LV hypertrophy that could not be explained by abnormal loading conditions.

“Noninvasive CMR shows an excellent diagnostic accuracy and yield regarding cardiac amyloidosis,” noted the researchers. “When combined with monoclonal protein studies, CMR can differentiate [transthyretin amyloidosis] from [light chain amyloidosis] with high accuracy and predictive value. However, invasive EMB remains a safe invasive gold standard and allows to differentiate cardiac amyloidosis from other cardiomyopathies that can also cause LV hypertrophy.”

Reference

Chatzantonis G, Bietenbeck M, Elsanhoury A, et al. Diagnostic value of cardiovascular magnetic resonance in comparison to endomyocardial biopsy in cardiac amyloidosis: A multi‑centre study [published online November 10, 2020]. Clin Res Cardiol. doi: 10.1007/s00392-020-01771-1