Intravenous Diltiazem Versus Metoprolol in Acute Rate Control of Atrial Fibrillation/Flutter and Rapid Ventricular Response: A Meta-Analysis of Randomized and Observational Studies

Background Atrial fibrillation (AF) and/or atrial flutter (AFL) with rapid ventricular response (RVR) is a condition that often requires urgent treatment. Although guidelines have recommendations regarding chronic rate control therapy, recommendations on the best choice for acute heart rate (HR) control in RVR are unclear.Methods A systematic search across multiple databases was performed for studies evaluating the outcome of HR control (defined as HR less than 110 bpm and/or 20% decrease from baseline HR). Included studies evaluated AF and/or AFL with RVR in a hospital setting, with direct comparison between intravenous (IV) diltiazem and metoprolol and excluded cardiac surgery and catheter ablation patients. Hypotension (defined as systolic blood pressure less than 90 mmHg) was measured as a secondary outcome. Two authors performed full-text article review and extracted data, with a third author mediating disagreements. Random effects models utilizing inverse variance weighting were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Heterogeneity was assessed using the I2 test.Results A total of 563 unique titles were identified through the systematic search, of which 16 studies (7 randomized and 9 observational) were included. In our primary analysis of HR control by study type, IV diltiazem was found to be more effective than IV metoprolol for HR control in randomized trials (OR 4.75, 95% CI 2.50-9.04 with I2 = 14%); however, this was not found for observational studies (OR 1.26, 95% CI 0.89-1.80 with I2 = 55%). In an analysis of observational studies, there were no significant differences between the two drugs in odds of hypotension (OR 1.12, 95% CI 0.51-2.45 with I2 = 18%).Conclusion While there was a trend toward improved HR control with IV diltiazem compared with IV metoprolol in randomized trials, this was not seen in observational studies, and there was no observed difference in hypotension between the two drugs.