Abstract 4142152: Different Determinants of Thrombotic Events in Transthyretin Cardiac Amyloidosis versus Other Left Ventricular Hypertrophy Phenotypes

Background: Thrombotic events (TE) are more frequent in cardiac amyloidosis (CA) as compared to other phenotypes of left ventricular hypertrophy (LVH) the absence of regional wall motion abnormalities. Aim: We sought to investigate the determinants of TE in patients with transthyretin cardiac amyloidosis (ATTR-CA). Method: Among subjects referred to our CA center those with LVH (interventricular septum thickness ≥ 1.2 cm) were included consecutively. Patients with hypertrophic obstructive cardiomyopathy, light chain CA or mitral valve disease were excluded. All subjects underwent echocardiography with speckle tracking imaging, Tc-99m pyrophosphate scintigraphy, serum and urine immune electrophoresis as per the registry protocol. Cardiac magnetic resonance imaging and endomyocardial biopsy were performed for diagnosis as needed. Control group consisted of subjects with non-amyloidosis LVH. Patients were followed-up over 5 years for TE (ischemic stroke, peripheral emboli, intracardiac thrombus). Results: In all, 149 ATTR-CA and 133 LVH patients (24 non-obstructive hypertrophic cardiomyopathy, 18 aortic stenosis, 91 hypertensive cardiomyopathy) were studied. Maximal LA volume index (LAVImax) did not increase significantly with atrial fibrillation (AF) in the ATTR-CA group, unlike in the LVH group. In the ATTR-CA group left atrial reservoir strain (LASr) was significantly reduced (10.2±4.8 vs 16.1±8.1, p<0.001) and LA stiffness (LASr/E/e’) significantly increased (2.4±1.6 vs 1.3±1.0, p<0.001) as compared to the LVH group. CHA 2 DS 2 -VASc was similar in both groups. (p=0.376). The comparison of patients with and without TE is presented in the table (Figure 1). In the ATTR-CA group, a higher percentage of patients (74%) were in or developed new AF versus the LVH group (55%) (p<0.001). In the LVH group, AF (hazard ratio (HR): 10, 95% confidence interval (CI), 2.4-42.2, p=0.024) and CHA 2 DS 2 -VASc (HR: 3.6, 95% CI, 1.52-8.48, p=034) were the independent determinants of TE. Whereas, in the ATTR-CA group LASr (HR: 0.85, 95% CI, 0.74-0.97, p=0.021) and LA stiffness (HR: 1.54, 95% CI, 1.18-1.99, p=0.001) emerged as independent determinants of TE among relevant covariates (AF, CHA 2 DS 2 -VASc, LAVImax), (Figure 2). Conclusion: In ATTR-CA LA remodeling is associated with TE irrespective of AF or CHA 2 DS 2 -VASc. Whereas AF and CHA 2 DS 2 -VASc are the main determinants of TE in other LVH phenotypes. These findings have potential implications to develop empirical anticoagulation strategies.