Non-alcoholic fatty liver disease (NAFLD) has emerged as a public health problem of epidemic proportions worldwide. Accumulating clinical and epidemiological evidence indicates that NAFLD is not only associated with liver-related morbidity and mortality but also with an increased risk of coronary heart disease (CHD), abnormalities of cardiac function and structure (e.g., left ventricular dysfunction and hypertrophy, and heart failure), valvular heart disease (e.g., aortic valve sclerosis) and arrhythmias (e.g., atrial fibrillation). Experimental evidence suggests that NAFLD itself, especially in its more severe forms, exacerbates systemic/hepatic insulin resistance, causes atherogenic dyslipidemia, and releases a variety of pro-inflammatory, pro-coagulant and pro-fibrogenic mediators that may play important roles in the pathophysiology of cardiac and arrhythmic complications. Collectively, these findings suggest that patients with NAFLD may benefit from more intensive surveillance and early treatment interventions to decrease the risk for CHD and other cardiac/arrhythmic complications. The purpose of this clinical review is to summarize the rapidly expanding body of evidence that supports a strong association between NAFLD and cardiovascular, cardiac and arrhythmic complications, to briefly examine the putative biological mechanisms underlying this association, and to discuss some of the current treatment options that may influence both NAFLD and its related cardiac and arrhythmic complications.

The relationship between non-alcoholic fatty liver disease (NAFLD) and atrial fibrillation (AF) in type 2 diabetes is currently unknown. We examined the relationship between NAFLD and risk of incident AF in people with type 2 diabetes. We prospectively followed for 10 years a random sample of 400 patients with type 2 diabetes, who were free from AF at baseline. A standard 12-lead electrocardiogram was undertaken annually and a diagnosis of incident AF was confirmed in affected participants by a single cardiologist. At baseline, NAFLD was defined by ultrasonographic detection of hepatic steatosis in the absence of other liver diseases. During the 10 years of follow-up, there were 42 (10.5%) incident AF cases. NAFLD was associated with an increased risk of incident AF (odds ratio [OR] 4.49, 95% CI 1.6–12.9, p<0.005). Adjustments for age, sex, hypertension and electrocardiographic features (left ventricular hypertrophy and PR interval) did not attenuate the association between NAFLD and incident AF (adjusted-OR 6.38, 95% CI 1.7–24.2, p = 0.005). Further adjustment for variables that were included in the 10-year Framingham Heart Study-derived AF risk score did not appreciably weaken this association. Other independent predictors of AF were older age, longer PR interval and left ventricular hypertrophy. Our results indicate that ultrasound-diagnosed NAFLD is strongly associated with an increased incidence of AF in patients with type 2 diabetes even after adjustment for important clinical risk factors for AF.

OBJECTIVE Data on cardiac function in patients with nonalcoholic fatty liver disease (NAFLD) are limited and conflicting. We assessed whether NAFLD is associated with abnormalities in cardiac function in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS We studied 50 consecutive type 2 diabetic individuals without a history of ischemic heart disease, hepatic diseases, or excessive alcohol consumption, in whom NAFLD was diagnosed by ultrasonography. A tissue Doppler echocardiography with myocardial strain measurement was performed in all patients. RESULTS Thirty-two patients (64%) had NAFLD, and when compared with the other 18 patients, age, sex, BMI, waist circumference, hypertension, smoking, diabetes duration, microvascular complication status, and medication use were not significantly different. In addition, the left ventricular (LV) mass and volumes, ejection fraction, systemic vascular resistance, arterial elasticity, and compliance were also not different. NAFLD patients had lower e′ (8.2 ± 1.5 vs. 9.9 ± 1.9 cm/s, P < 0.005) tissue velocity, higher E-to-e′ ratio (7.90 ± 1.3 vs. 5.59 ± 1.1, P < 0.0001), a higher time constant of isovolumic relaxation (43.1 ± 10.1 vs. 33.2 ± 12.9 ms, P < 0.01), higher LV–end diastolic pressure (EDP) (16.5 ± 1.1 vs. 15.1 ± 1.0 mmHg, P < 0.0001), and higher LV EDP/end diastolic volume (0.20 ± 0.03 vs. 0.18 ± 0.02 mmHg, P < 0.05) than those without steatosis. Among the measurements of LV global longitudinal strain and strain rate, those with NAFLD also had higher E/global longitudinal diastolic strain rate during the early phase of diastole (E/SR_E). All of these differences remained significant after adjustment for hypertension and other cardiometabolic risk factors. CONCLUSIONS Our data show that in patients with type 2 diabetes and NAFLD, even if the LV morphology and systolic function are preserved, early features of LV diastolic dysfunction may be detected.

OBJECTIVE: Recent studies have suggested that nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of heart rate–corrected QT interval prolongation and atrial fibrillation in patients with type 2 diabetes. Currently, no data exist regarding the relationship between NAFLD and ventricular arrhythmias in this patient population. RESEARCH DESIGN AND METHODS: We retrospectively analyzed the data of 330 outpatients with type 2 diabetes without preexisting atrial fibrillation, end-stage renal disease, or known liver diseases who had undergone 24-h Holter monitoring for clinical reasons between 2013 and 2015. Ventricular arrhythmias were defined as the presence of nonsustained ventricular tachycardia (VT), >30 premature ventricular complexes (PVCs) per hour, or both. NAFLD was diagnosed by ultrasonography. RESULTS: Compared with patients without NAFLD, those with NAFLD (n = 238, 72%) had a significantly higher prevalence of >30 PVCs/h (19.3% vs. 6.5%, P < 0.005), nonsustained VT (14.7% vs. 4.3%, P < 0.005), or both (27.3% vs. 9.8%, P < 0.001). NAFLD was associated with a 3.5-fold increased risk of ventricular arrhythmias (unadjusted odds ratio [OR] 3.47 [95% CI 1.65–7.30], P < 0.001). This association remained significant even after adjusting for age, sex, BMI, smoking, hypertension, ischemic heart disease, valvular heart disease, chronic kidney disease, chronic obstructive pulmonary disease, serum γ-glutamyltransferase levels, medication use, and left ventricular ejection fraction (adjusted OR 3.01 [95% CI 1.26–7.17], P = 0.013). CONCLUSIONS: This is the first observational study to show that NAFLD is independently associated with an increased risk of prevalent ventricular arrhythmias in patients with type 2 diabetes.