Abstract
BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is estimated to affect approximately 25% of the global population. Both, coronary artery disease and NAFLD are linked to underlying insulin resistance and inflammation as drivers of the disease. Coronary flow reserve parameters, including coronary flow reserve velocity (CFRV), baseline diastolic peak flow velocity (DPFV), and hyperemic DPFV, are noninvasive markers of coronary microvascular circulation. The existing literature contains conflicting findings regarding these parameters in NAFLD patients. METHODS: A comprehensive systematic search was conducted on major electronic databases from inception until May 8, 2024, to identify relevant studies. We pooled the standardized mean differences (SMD) with 95% confidence intervals (CI) using the inverse-variance random-effects model. Statistical significance was set at P < .05. RESULTS: Four studies with 1139 participants (226 with NAFLD and 913 as controls) were included. NAFLD was associated with a significantly lower CFRV (SMD: -0.77; 95% CI: -1.19, -0.36; P < .0002) and hyperemic DPFV (SMD: -0.73; 95% CI: -1.03, -0.44; P < .00001) than the controls. NAFLD demonstrated a statistically insignificant trend toward a reduction in baseline DPFV (SMD: -0.09; 95% CI: -0.38, 0.19; P = .52) compared to healthy controls. CONCLUSION: Patients with NAFLD are at a higher risk of coronary microvascular dysfunction, as demonstrated by reduced CFRV and hyperemic DPFV. The presence of abnormal coronary flow reserve in patients with NAFLD provides insights into the higher rates of cardiovascular disease in these patients. Early aggressive targeted interventions for impaired coronary flow reserve in subjects with NAFLD may lead to improvement in clinical outcomes.