Analysis of clinical features and prognosis in cardiac amyloidosis patients from Spanish hospitals (2016–2021)

Introduction and objectives

Cardiac amyloidosis (CA) is a prevalent yet underdiagnosed heart condition characterized by the abnormal accumulation of amyloid fibres, frequently resulting in heart failure (HF), particularly in older people. Despite advancements in non-invasive diagnostic techniques and treatments, the epidemiology of CA patients remains inadequately understood. This nationwide retrospective observational study sought to comprehensively investigate CA patients’ characteristics, mortality, and readmission patterns.

Methods

A retrospective observational study encompassed all patients hospitalized with CA between 2016 and 2021 across Spanish hospitals. Standardized incidence rates were calculated using age and sex-adjusted methods, utilizing the Spanish population as the reference. The investigation delved into demographic variables, comorbidities, mortality during the index episode, and 30 and 365-day readmissions for circulatory system diseases. Predictors of readmission were also examined.

Results

A total of 5739 index episodes were identified, with CA being the primary cause of admission in 14.1% of cases. The mean age was 81.4 ± 9.9 years, predominantly males (70.3%). The age and sex-standardized hospital attendance rate was 3.90 admissions per 100,000 population (95% CI: 3.82–3.98), higher in males. Common comorbidities included HF (96.4%), atrial fibrillation (46.3%), and renal failure (44.4%). The mortality rate during the index episode was 11.7%, with cardiogenic shock (OR: 9.03; 95% CI: 4.22–19.32) and major psychiatric disorders (OR: 3.36; 95% CI: 1.42–7.94) identified as predictors.

Over the follow-up period, 13.1% were readmitted at 30 days and 36.6% at 365. Nephritis (IRR: 2.05; 95% CI: 1.42–2.96) and asthma (IRR: 1.52; 95% CI 1.11–2.07) were associated with increased 30-day readmissions, while renal failure (IRR: 1.43; 95% CI: 1.28–1.59) and chronic pulmonary disease (IRR: 1.40; 95% CI: 1.18–1.67) were linked to higher 365-day readmissions. Predictors of mortality risk in 365-day readmissions included advanced cancer (HR: 1.31; 95% CI: 1.00–1.71), cardiogenic shock in the index episode (HR: 2.72; 95% CI: 1.33–5.57), and a higher number of readmissions during that period (HR: 1.64; 95% CI: 1.56–1.73).

Conclusions

This study contributes valuable insights into the significant prevalence of CA, which is often overlooked and underestimated. Afflicting predominantly elderly males with concomitant HF and multiple comorbidities, CA poses a significant clinical challenge. The findings underscore the need for enhanced awareness, early detection, and a multidisciplinary approach to manage this complex cardiac condition.