Genetic Etiology for Alcohol-Induced Cardiac Toxicity

BACKGROUND

Alcoholic cardiomyopathy (ACM) is defined by a dilated and impaired left ventricle due to chronic excess alcohol consumption. It is largely unknown which factors determine cardiac toxicity on exposure to alcohol.

OBJECTIVES

This study sought to evaluate the role of variation in cardiomyopathy-associated genes in the pathophysiology of ACM, and to examine the effects of alcohol intake and genotype on dilated cardiomyopathy (DCM) severity.

METHODS

The authors characterized 141 ACM cases, 716 DCM cases, and 445 healthy volunteers. The authors compared the prevalence of rare, protein-altering variants in 9 genes associated with inherited DCM. They evaluated the effect of genotype and alcohol consumption on phenotype in DCM.

RESULTS

Variants in well-characterized DCM-causing genes were more prevalent in patients with ACM than control subjects (13.5% vs. 2.9%; p = 1.2 ×10^-5), but similar between patients with ACM and DCM (19.4%; p = 0.12) and with a predominant burden of titin truncating variants (TTNtv) (9.9%). Separately, we identified an interaction between TTN genotype and excess alcohol consumption in a cohort of DCM patients not meeting ACM criteria. On multivariate analysis, DCM patients with a TTNtv who consumed excess alcohol had an 8.7% absolute reduction in ejection fraction (95% confidence interval: -2.3% to -15.1%; p < 0.007) compared with those without TTNtv and excess alcohol consumption. The presence of TTNtv did not predict phenotype, outcome, or functional recovery on treatment in ACM patients.

CONCLUSIONS

TTNtv represent a prevalent genetic predisposition for ACM, and are also associated with a worse left ventricular ejection fraction in DCM patients who consume alcohol above recommended levels. Familial evaluation and genetic testing should be considered in patients presenting with ACM.

Prognostic Impact and Predictors of Ejection Fraction Recovery in Patients With Alcoholic Cardiomyopathy

INTRODUCTION AND OBJECTIVES

Recovery of left ventricular ejection fraction (LVEF) has been described in alcoholic cardiomyopathy (ACM) after a period of alcohol withdrawal. Nevertheless, the prognostic impact of LVEF recovery in ACM and its determinants have not been studied. We sought to define the role of LVEF improvement in the long-term outcome of ACM and to identify predictors of LVEF recovery in these patients.

METHODS

We evaluated 101 ACM patients during a median follow-up period of 82 months [interquartile range 36-134].

RESULTS

At latest follow-up, 42 patients (42%) showed substantial LVEF recovery defined as an absolute increase in LVEF ≥ 10% to a final value of ≥ 40%. Patients who recovered LVEF had better outcomes than patients who did not (heart transplant or cardiovascular death 1% vs 30%; P <.001). A QRS with <120ms (OR, 6.68; 95%CI, 2.30-19.41), beta-blocker therapy (OR, 3.01; 95%CI, 1.09-8.28), and the absence of diuretics (OR, 3.35; 95%CI, 1.08-10.42) predicted LVEF recovery in multivariate analysis. Although alcohol cessation did not predict LVEF recovery, none of the patients (n=6) who persisted with heavy alcohol consumption recovered LVEF. The rate of patients who recovered LVEF did not differ between abstainers and moderate drinkers (44% vs 45%; P=.9).

CONCLUSIONS

The LVEF recovery is associated with an excellent prognosis in ACM. Beta-blocker treatment, QRS <120ms and absence of diuretics are independent predictors of LVEF recovery. LVEF recovery is similar in moderate drinkers and abstainers.

Wild-type transthyretin amyloidosis as a cause of heart failure with preserved ejection fraction

AIMS

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous clinical syndrome with multiple underlying causes. Wild-type transthyretin (TTR) amyloidosis (ATTRwt) is an underdiagnosed cause of HFpEF that might benefit from new specific treatments. ATTRwt can be diagnosed non-invasively by (99m)Tc-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) scintigraphy. We sought to determine the prevalence of ATTRwt among elderly patients admitted due to HFpEF.

METHODS AND RESULTS

We prospectively screened all consecutive patients ≥60 years old admitted due to HFpEF [left ventricular (LV) ejection fraction ≥50%] with LV hypertrophy (≥12 mm). All eligible patients were offered a (99m)Tc-DPD scintigraphy. The study included 120 HFpEF patients (59% women, 82 ± 8 years). A total of 16 patients (13.3%; 95% confidence interval: 7.2-19.5) showed a moderate-to-severe uptake on the (99m)Tc-DPD scintigraphy. All patients with a positive scan underwent genetic testing of the TTR gene, and no mutations were found. An endomyocardial biopsy was performed in four patients, confirming ATTRwt in all cases. There were no differences in age, gender, hypertension, diabetes, coronary artery disease, or atrial fibrillation between ATTRwt patients and patients with other HFpEF forms. Although patients with ATTRwt exhibited higher median N-terminal pro-brain natriuretic peptide (6467 vs. 3173 pg/L; P = 0.019), median troponin I (0.135 vs. 0.025 µg/L; P < 0.001), mean LV maximal wall thickness (17 ± 3.4 vs. 14 ± 2.5 mm; P = 0.001), rate of pericardial effusion (44 vs. 19%; P = 0.047), and rate of pacemakers (44 vs. 12%; P = 0.004), clinical overlap between ATTRwt and other HFpEF forms was high.

CONCLUSION

ATTRwt is an underdiagnosed disease that accounts for a significant number (13%) of HFpEF cases. The effect of emerging TTR-modifying drugs should be evaluated in these patients.

Alcoholic cardiomyopathy

Alcohol is the most frequently consumed toxic substance in the world. Low to moderate daily intake of alcohol has been shown to have beneficial effects on the cardiovascular system. In contrast, exposure to high levels of alcohol for a long period could lead to progressive cardiac dysfunction and heart failure. Cardiac dysfunction associated with chronic and excessive alcohol intake is a specific cardiac disease known as alcoholic cardiomyopathy (ACM). In spite of its clinical importance, data on ACM and how alcohol damages the heart are limited. In this review, we evaluate available evidence linking excessive alcohol consumption with heart failure and dilated cardiomyopathy. Additionally, we discuss the clinical presentation, prognosis and treatment of ACM.

Genetics in dilated cardiomyopathy

Discoveries made during the last 20 years have revealed a genetic origin in many cases of dilated cardiomyopathy (DCM). Currently, over 40 genes have been associated with the disease. Mutations in DCM-causing genes induce the condition through a variety of different pathological pathways with complex and not completely understood mechanisms. Genes that encode for sarcomeric, cytoskeletal, nuclear membrane, dystrophin-associated glycoprotein complex and desmosomal proteins are the principal genes involved. In this review we discuss the most frequent DCM-causing genes. We propose a classification in which DCM genes are considered as being major or minor genes according to their mutation frequency and the available supporting evidence. The main phenotypic characteristics associated with each gene are discussed.