Clinical Profile and Outcomes of Patients with Cardiac Amyloidosis – Spanish Experience from Real Practice

Cardiac Amyloidosis – Heterogeneous and Still Underdiagnosed

The most common subtypes of amyloidosis affecting the heart muscle are AL amyloidosis from immunoglobulin light chains due to plasma cell dyscrasia and TTR amyloidosis caused by transthyretin (TTR) deposition. TTR amyloidosis (ATTR) can be hereditary, caused by mutations in the TTR gene, or acquired (ATTRwt, formerly known as senile amyloidosis). Historically, AL amyloidosis was considered the most common; however, with an aging population and advances in noninvasive diagnostics, ATTR is now considered the most common form of the disease.

Cardiac amyloidosis remains a disease with significant diagnostic delay. This is partly due to the traditional view of it as an incurable disease and the complexity of the diagnostic process, which until recently required histologic examination of an endomyocardial biopsy. However, recently it has become possible for many patients to reach a definitive diagnosis without the need for histologic proof, and in the last decade, there have been new promising therapeutic options for both AL and ATTR. Early diagnosis is thus crucial for effective therapy.

Due to the relatively small number of published experiences with the diagnosis and treatment of patients with cardiac amyloidosis, authors from the University Hospital in Madrid decided to conduct a retrospective analysis of the clinical characteristics, outcomes, and survival of patients with cardiac amyloidosis followed in this center over a ten-year period.

Evaluated Data

A descriptive observational retrospective study analyzed data from all consecutive patients diagnosed with cardiac amyloidosis at the University Hospital Puerta de Hierro Majadahonda from 2008–2018. Patients diagnosed using both invasive and noninvasive techniques were included. Patients without cardiac manifestation (in case of mutated TTR or presence of AL) were excluded.

Demographic data, time to death from any cause or heart transplantation, and clinical parameters (presence of heart failure at diagnosis, NYHA functional class, NT-proBNP level, glomerular filtration rate, and left ventricular ejection fraction) were monitored.

Findings

The analysis included 180 patients, of which 36% were diagnosed with AL (50% men, average age 65 ± 11 years) and 64% with ATTR (72% men, average age 79 ± 11 years, 15.5% of whom had hereditary ATTR).

The most common symptom in both groups was heart failure (81% in AL and 45% in ATTR; p < 0.01). Other symptoms in patients with ATTR included atrial arrhythmias (16%) and conduction disturbances (6%). A total of 40% had another cardiovascular diagnosis in their medical history. In 75% of patients with ATTR, the diagnosis was made noninvasively.

Diagnostic delay was higher in patients with ATTR compared to AL (2.8 ± 4.3 vs. 0.6 ± 0.7 years; p < 0.001), but mortality was higher in patients with AL (48 vs. 32%; p = 0.028).

Independent predictors of mortality were AL subtype cardiac amyloidosis (hazard ratio [HR] 6.16; 95% confidence interval [CI] 1.56–24.3; p = 0.01), female gender (HR 2.35; 95% CI 1.24–4.46; p = 0.01), and NYHA functional class III–IV (HR 2.07; 95% CI 1.11–3.89; p = 0.02).

Conclusion

Cardiac amyloidosis presents a clinical challenge due to the great variability of symptoms depending on its subtype, leading to diagnostic delay and high mortality. Given the availability of new treatment modalities, early diagnosis is crucial for successful therapy initiation.

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Source: López-Sainz Á., Hernandez-Hernandez A., Gonzalez-Lopez E. et al. Clinical profile and outcome of cardiac amyloidosis in a Spanish referral center. Rev Esp Cardiol (Engl Ed) 2021; 74 (2): 149–158, doi: 10.1016/j.rec.2019.12.020.