Prevalence and Prognostic Significance of Restriction Versus Systolic Dysfunction in Patients With Transthyretin and Light Chain Cardiac Amyloidosis

Background: The tenet of cardiac amyloidosis (CA) as a paradigm of heart failure with restrictive ventricular physiology and preserved systolic function has come under scrutiny. We aimed to evaluate the prevalence and clinical significance of left ventricular (LV) systolic dysfunction versus restriction in a large real-world cohort with CA, assessed at the time of diagnosis. Methods: We retrospectively analyzed 540 TTR (transthyretin)-CA and 280 AL (light chain)-CA. Patients were divided into 3 LV phenotypes: (1) preserved LV function: LV ejection fraction >40% associated with grade I diastolic dysfunction; (2) restriction: LV ejection fraction >40% associated with grade II/III diastolic dysfunction; (3) systolic dysfunction: LV ejection fraction ≤40% irrespective of diastolic function. We analyzed the progression from preserved LV function towards the other 2 LV phenotypes and survival free from the composite end point of all-cause mortality and heart transplantation. Results: In TTR-CA, the prevalence of preserved LV function was 32.0%, restriction was 56.1%, and systolic dysfunction was 11.9%. Among patients with preserved LV function, at the last evaluation, the conversion rate to restriction was 16.3% and to systolic dysfunction was 1.8%. The 3-year freedom from the composite end point was 75%, 61%, and 44%, respectively. In AL-CA, the prevalence of preserved LV function was 32.9%, restriction was 58.6%, and systolic dysfunction was 8.5%. Among patients with preserved LV function, at the last evaluation, the conversion rate to restriction was 12.9%, and to systolic dysfunction was none. The 3-year freedom from the composite end point was 46%, 32%, and 21%, respectively. Conclusions: Restriction was the most common presenting phenotype, while preserved LV function represented approximately one-third. The rate of progression from preserved LV function towards restriction was high, whereas it was limited towards systolic dysfunction. Although patients with preserved LV function presented the best event-free survival, considering all-cause mortality and heart transplantation, compared with restriction or systolic dysfunction, these phenotypes are not independent predictors of this composite end point.