Myocardial Amyloid Quantification with Look-Locker Magnetic Resonance Sequence in Cardiac Amyloidosis. Diagnostic Accuracy in Clinical Practice and Histological Validation.

BACKGROUND: Cardiac magnetic resonance (CMR) has demonstrated its utility in the noninvasive diagnosis of cardiac amyloidosis (CA). Our aim was to evaluate the ability of standard Look-Locker sequences to quantify amyloid deposition in CA. METHODS AND RESULTS: Consecutive patients referred for CMR for possible CA were retrospectively evaluated. Positive cardiac biopsy and/or typical pattern of late gadolinium enhancement were required for the diagnosis of CA. Postcontrast T1 values were obtained from Look-Locker sequences and correlated with markers of severity of disease and major events. When cardiac biopsies were available, histological validation was determined. A total of 174 patients were included. A final diagnosis of CA was reached in 37.4%. Myocardial and endocardial T1 times, as well as the respective ratios with blood and skeletal muscle, were lower among patients with CA and demonstrated good diagnostic performance. The best parameters were myocardial/blood (area under the curve 0.83; P < .001) and endocardial/blood (area under the curve 0.84; P < .001) T1 ratios. Among patients with CA, no associations were found between T1 ratios either with markers of amyloid burden or with prognostic variables. However, all T1 indexes showed significant correlations with histological quantification of amyloid deposition. CONCLUSIONS: Look-Looker derived postcontrast T1 shows good diagnostic accuracy to detect CA and correlation with histological amyloid burden.

Cardiac magnetic resonance evaluation of left ventricular remodelling distribution in cardiac amyloidosis.

BACKGROUND: Cardiac amyloidosis (CA) is associated with typical morphological features on echocardiography, including concentric LV hypertrophy (LVH). Cardiac magnetic resonance (CMR) can accurately depict anatomy in different cardiomyopathies. Our aim was to describe the morphological features and remodelling patterns of CA with CMR, and establish their diagnostic accuracy, as well as the value of traditional diagnostic criteria derived from echocardiography and electrocardiography. METHODS: Consecutive patients referred for CMR for possible CA were retrospectively evaluated. The diagnosis of CA was established in the presence of a positive cardiac biopsy and/or a typical pattern of myocardial late gadolinium enhancement. Morphological parameters were obtained from standard cine sequences. The presence and distribution of LVH, relative wall thickness (RWT) and LV remodelling patterns were determined. RESULTS: 130 patients (92 males (70.8%), age 64±13 years) were included. CA was diagnosed in 51 (39.2%). Patients with CA had increased LV wall thickness and LV mass index. An LV remodelling pattern different from concentric LVH was found in 42% of patients with CA, and asymmetric LVH was noted in 68.6%. A model including RWT, asymmetric LVH, and LVMI showed diagnostic accuracy of 88%, sensitivity of 67% and specificity of 86% for CA detection. Traditional diagnostic criteria for CA showed high specificity but poor sensitivity. CONCLUSIONS: Asymmetric LVH and remodelling patterns different from concentric LVH are common in CA. Increased LV mass index, increased RWT, and asymmetric LVH are independently associated with the diagnosis. Traditional diagnostic criteria show poor sensitivity.