Differences in the characteristics and contemporary cardiac outcomes of patients with light-chain versus transthyretin cardiac amyloidosis.

Aims: To compare the baseline cardiovascular characteristics of immunoglobulin light-chain (AL) and amyloid transthyretin (ATTR) cardiac amyloidosis (CA) and to investigate patients' contemporary cardiac outcomes.

Methods: Single-center analysis of clinical, laboratory, echocardiographic and cardiac magnetic resonance imaging (CMRi) characteristics of AL and ATTR-CA patients' cohort (years 2013-2020).

Results: Included were 67 CA patients of whom 31 (46%) had AL-CA and 36 (54%) had ATTR-CA. Patients with ATTR-CA versus AL-CA were older (80 (IQR 70, 85) years versus 65 (IQR 60, 71) years, respectively, p<0.001) with male predominance (p = 0.038). Co-morbidities in ATTR-CA patients more frequently included diabetes mellitus (19% versus 3.0%, respectively, p = 0.060) and coronary artery disease (39% versus 10%, respectively, p = 0.010). By echocardiography, patients with ATTR-CA versus AL-CA had a trend to worse left ventricular (LV) ejection function (50 (IQR 40, 55)% versus 60 (IQR 45, 60)%, respectively, p = 0.051), yet comparable LV diastolic function. By CMRi, left atrial area (31 (IQR 27, 36)cm2 vs. 27 (IQR 23, 30)cm2, respectively, p = 0.015) and LV mass index (109 (IQR 96, 130)grams/m2 vs. 82 (IQR 72, 98)grams/m2, respectively, p = 0.011) were increased in patients with ATTR-CA versus AL-CA. Nevertheless, during follow-up (median 20 (IQR 10, 38) months), patients with AL-CA were more frequently admitted with heart failure exacerbations (HR 2.87 (95% CI 1.42, 5.81), p = 0.003) and demonstrated increased mortality (HR 2.51 (95%CI 1.19, 5.28), p = 0.015).

Conclusion: Despite the various similarities of AL-CA and ATTR-CA, these diseases have distinct baseline cardiovascular profiles and different heart failure course, thus merit tailored-cardiac management.