Delayed hyper-enhancement magnetic resonance imaging provides incremental diagnostic and prognostic utility in suspected cardiac amyloidosis

Abstract

Objectives: We sought to assess the diagnostic accuracy and incremental prognostic value of delayed hyper-enhancement cardiac magnetic resonance (DHE-CMR) compared with electrocardiographic and transthoracic echocardiographic (TTE) parameters in such patients.

Background: Utility of DHE-CMR in the diagnosis of patients with suspected cardiac amyloidosis (CA) has recently been demonstrated, but its incremental prognostic utility is unclear.

Methods: Forty-seven consecutive patients (mean age 63 years, 70% men, 55% New York Heart Association functional class >II) with suspected CA who underwent electrocardiography (ECG), TTE, DHE-CMR, and biopsy (38 endomyocardial, 9 extracardiac) were studied. Low voltage on ECG was defined as S-wave in lead V(1) + R-wave in lead V(5) or V(6) <15 mm. TTE parameters, including deceleration time, E/E' ratio, and diastolic grade were recorded. CMR was considered positive with diffuse DHE of the subendocardium extending to adjacent myocardium. All-cause mortality was ascertained.

Results: In the study population, 59% had low voltage on ECG, 30% had abnormal deceleration time < OR = 150 ms, 38% had E/E' ratio >15, and 47% had advanced (pseudonormal or restrictive) diastology.The diagnostic accuracy of DHE-CMR in patients undergoing endomyocardial biopsy was as follows: sensitivity 88%, specificity 90%, positive predictive value 88%, and negative predictive value 90%. On multivariable logistic regression testing of the diagnostic ability of various noninvasive imaging parameters, only DHE-CMR was significant (Wald chi-square statistic 9.6, p < 0.01). At 1-year post-biopsy, there were 9 (19%) deaths. On Cox proportional hazards analysis, only positive DHE-CMR was a predictor of 1-year mortality (Wald chi-square statistic 4.91, p = 0.03).

Conclusions: A characteristic DHE-CMR pattern is more accurate for diagnosis and is a stronger predictor of 1-year mortality in patients with suspected CA as compared with other noninvasive parameters.