An Unusual Case of Heart Failure: Sometimes When You Hear Hoof Beats You Should Think of Zebras

Clinical spectrum of Transthyretin amyloidogenic mutations among diverse population origins

PURPOSE

Coding mutations in the Transthyretin (TTR) gene cause a hereditary form of amyloidosis characterized by a complex genotype-phenotype correlation with limited information regarding differences among worldwide populations.

METHODS

We compared 676 diverse individuals carrying TTR amyloidogenic mutations (rs138065384, Phe44Leu; rs730881165, Ala81Thr; rs121918074, His90Asn; rs76992529, Val122Ile) to 12,430 non-carriers matched by age, sex, and genetically-inferred ancestry to assess their clinical presentations across 1,693 outcomes derived from electronic health records in UK biobank.

RESULTS

In individuals of African descent (AFR), Val122Ile mutation was linked to multiple outcomes related to the circulatory system (fold-enrichment = 2.96, p = 0.002) with the strongest associations being cardiac congenital anomalies (phecode 747.1, p = 0.003), endocarditis (phecode 420.3, p = 0.006), and cardiomyopathy (phecode 425, p = 0.007). In individuals of Central-South Asian descent (CSA), His90Asn mutation was associated with dermatologic outcomes (fold-enrichment = 28, p = 0.001). The same TTR mutation was linked to neoplasms in European-descent individuals (EUR, fold-enrichment = 3.09, p = 0.003). In EUR, Ala81Thr showed multiple associations with respiratory outcomes related (fold-enrichment = 3.61, p = 0.002), but the strongest association was with atrioventricular block (phecode 426.2, p = 2.81 × 10- 4). Additionally, the same mutation in East Asians (EAS) showed associations with endocrine-metabolic traits (fold-enrichment = 4.47, p = 0.003). In the cross-ancestry meta-analysis, Val122Ile mutation was associated with peripheral nerve disorders (phecode 351, p = 0.004) in addition to cardiac congenital anomalies (fold-enrichment = 6.94, p = 0.003).

CONCLUSIONS

Overall, these findings highlight that TTR amyloidogenic mutations present ancestry-specific and ancestry-convergent associations related to a range of health domains. This supports the need to increase awareness regarding the range of outcomes associated with TTR mutations across worldwide populations to reduce misdiagnosis and delayed diagnosis of TTR-related amyloidosis.

Clinical Features, Genetic Findings, and Risk Stratification in Arrhythmogenic Right Ventricular Cardiomyopathy: Data From a Brazilian Cohort

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC), a rare inherited disease, causes ventricular tachycardia, sudden cardiac death, and heart failure (HF). We investigated ARVC clinical features, genetic findings, natural history, and the occurrence of life-threatening arrhythmic events (LTAEs), HF death, or heart transplantation (HF-death/HTx) to identify risk factors.

METHODS

The clinical course of 111 consecutive patients with definite ARVC, predictors of LTAE, HF-death/HTx, and combined events were analyzed in the entire cohort and in a subgroup of 40 patients without sustained ventricular arrhythmia before diagnosis.

RESULTS

The 5-year cumulative probability of LTAE was 30% and HF-death/HTx was 10%. Predictors of HF-death/HTx were reduced right ventricle ejection fraction (HR: 0.93; P=0.010), HF symptoms (HR: 4.37; P=0.010), epsilon wave (HR: 4.99; P=0.015), and number of leads with low QRS voltage (HR: 1.28; P=0.001). Each additional lead with low QRS voltage increased the risk of HF-death/HTx by 28%. Predictors of LTAE were prior syncope (HR: 1.81; P=0.040), number of leads with T wave inversion (HR: 1.17; P=0.039), low QRS voltage (HR: 1.12; P=0.021), younger age (HR: 0.97; P=0.006), and prior ventricular arrhythmia/ventricular fibrillation (HR: 2.45; P=0.012). Each additional lead with low QRS voltage increased the risk of LTAE by 17%. In patients without ventricular arrhythmia before clinical diagnosis of ARVC, the number of leads with low QRS voltage (HR: 1.68; P=0.023) was independently associated with HF-death/HTx.

CONCLUSIONS

Our study demonstrated the characteristics of a specific cohort with a high prevalence of arrhythmic burden at presentation, male predominance, younger age and HF severe outcomes. Our main results suggest that the presence and extension of low QRS voltage can be a risk predictor for HF-death/HTx in ARVC patients, regardless of the arrhythmic risk. This study can contribute to the global ARVC risk stratification, adding new insights to the international current scientific knowledge.