Pre-Treatment with IV Calcium Prior to IV Diltiazem Prevents Hypotension in AF

Clinical question: Can pre-treatment with IV calcium prevent hypotension in patients receiving IV diltiazem for atrial fibrillation (AF) or atrial flutter?

Background: AF is the most commonly treated arrhythmia in EDs. Diltiazem is a first-line agent for rate control of AF with rapid ventricular response (RVR, heart rate over 120 beats per minute [bpm] at rest) due to its negative chronotropic effects at the sinus node. However, it can also cause vasodilation by acting on vascular smooth-muscle calcium channels, often resulting in hypotension. While the efficacy of IV calcium in mitigating verapamil-induced hypotension is well established, data supporting its use alongside diltiazem have been limited. Prior studies were constrained by the use of relatively low doses of IV calcium (90 mg).

Study design: Double-blinded, prospective-cohort, placebo-controlled, single-center, randomized, controlled trial

Setting: University of Haseki Emergency Department, Istanbul, Türkiye

Synopsis: A total of 217 adult patients presenting to the ED with atrial fibrillation or flutter, heart rate over 120 bpm, and systolic blood pressures (SBP) between 90 and 180 mmHg were randomized to receive either saline placebo, 90 mg IV calcium chloride (CaCl), or 180 mg IV CaCl prior to receiving IV diltiazem. Patients requiring cardioversion due to hemodynamic instability and those taking beta-blockers or other rate-control agents were excluded. Blood pressure and heart rate were recorded at five, 10, and 15 minutes post-diltiazem.

The placebo group experienced a maximum mean SBP drop of 15 mmHg, compared to 9 mmHg in the 90 mg CaCl group, and no SBP change in the 180 mg CaCl group. All groups achieved heart rate reduction to less than 110 bpm. However, the mean heart rate at 15 minutes was slightly lower in the placebo and 90 mg groups (96 bpm and 99 bpm, respectively) than in the 180 mg group (105 bpm). There were no significant differences in the need for repeat diltiazem dosing across groups.

Bottom line: In this small, single-center study, pre-treatment with IV calcium, particularly at a dose of 180 mg, successfully blunted the hypotensive effects of IV diltiazem without substantially impairing heart rate control. Hospitalists may consider using IV calcium gluconate, when available, instead of calcium chloride due to its lower risk of infusion-related adverse effects.

Citation: Az A, et al. Reducing diltiazem-related hypotension in atrial fibrillation: role of pretreatment intravenous calcium. Am J Emerg Med. 2025;88:23-28. doi:10.1016/j.ajem.2024.11.033.

Dr. Advani is an associate director of the hospitalist service at Yale New Haven Hospital, an assistant clinical professor at Yale School of Medicine, and co-firm chief of Yale’s Hospital Medicine Firm, all in New Haven, Conn.