Dennis J. Baumgardner, MD, Clinician Researcher Award Oral Presentation

Background/Significance:

Hypotension is a common adverse effect of calcium channel blockers (CCBs) when treating atrial fibrillation with rapid ventricular response (AFRVR). Previous data describes the use of pretreatment with intravenous calcium prior to CCBs to ameliorate this adverse effect. However, the majority of literature evaluated verapamil, had variable calcium dosing strategies, and a paucity of data is available.

Purpose:

The objective of this study was to compare the efficacy of calcium pretreatment in decreasing the incidence of drug-induced hypotension after diltiazem administration for the treatment of AFRVR.

Methods:

This is a prospective, randomized, double-blind trial comparing 1 g of calcium gluconate to placebo (50 ml 0.9% NaCl) for patients presenting with AFRVR immediately prior to diltiazem administration. The primary outcome is mean difference in systolic blood pressure (SBP mmHg) from baseline compared to 5 and 15 minutes after diltiazem administration. Secondary endpoints included changes in heart rate, cardiac rhythm, and the clinical need for rescue medications. Descriptive statistics, t-test, chi-square and ANOVA tests were used for data analysis. All tests were two-tailed and p-values of 0.05 were considered statistically significant. A power analysis indicated the need for 92 subjects to detect a 10 mmHg difference in SBP.

Results:

A total of 83 patients (n=44 and n=39 for calcium pretreatment and placebo, respectively) were enrolled as of June 30th, 2024. A total of nine patients were excluded prior to study drug administration for change in hemodynamic status and consent withdrawal. The mean decrease in SBP at 5 minutes was 11.8 and 19.5 in the calcium and placebo arms respectively (p=0.029). Similarly, the mean decrease in SBP at 15 minutes was 7.8 and 16.3 in the calcium and placebo arms respectively (p=0.011). The mean difference in HR 15 minutes was 43.1 in the calcium arm and 33.8 placebo arm (p=0.043). No significant difference in incidence of hypotension or other serious adverse effects were observed in any of the groups.

Conclusion:

Calcium demonstrated a protective effect on systolic blood pressures at both 5 and 10 minutes after administration of diltiazem. A greater decrease in heart rate was observed in the calcium arm for HR at 15 minutes. No differences were observed in adverse effects.