The following is a summary of “Effect of serum calcium level on the success of diltiazem treatment: A retrospective cohort study,” published in the September 2023 issue of Emergency Medicine by Küçük, et al.

Diltiazem is a commonly used antiarrhythmic medication for managing atrial fibrillation (AFib) with rapid ventricular response (RVR). Its mechanism of action involves blocking L-type calcium channels, which leads to the inhibition of calcium influx into the cytosol. However, the impact of serum calcium levels on the effectiveness of intravenous (IV) diltiazem treatment for AFib with RVR has not been explored in clinical practice. For a study, researchers sought to investigate the relationship.

The retrospective study was conducted at a single center. The data of 349 patients who arrived at the emergency department with AFib and RVR and were treated with diltiazem were analyzed retrospectively. Treatment success with diltiazem was defined as the restoration of normal sinus rhythm, a heart rate reduction to below 100 beats/min, or a heart rate decrease of more than 20%, provided it was below 120 beats/min. Ionized calcium levels were recorded, and the relationship between serum calcium levels and the efficacy of diltiazem treatment was assessed.

Of the patients, 55% were female, and the median age was 75 years. The overall response rate to diltiazem treatment was 67.3%. The median ionized calcium levels in the group that responded to diltiazem treatment (n = 235) was 1.14 mmol/L (IQR: 0.12), while in the group that did not respond to diltiazem treatment (n = 114), it was 1.11 mmol/L (IQR: 0.12) (P = 0.322). Patients were categorized into three groups based on low, normal, and high calcium levels according to hospital laboratory reference levels. The response rate to diltiazem treatment was 61.4% for patients with low ionized calcium levels, 76.1% for patients with normal ionized calcium levels, and 40.0% for patients with high ionized calcium levels. Patients with normal ionized calcium levels exhibited a higher response rate to diltiazem treatment compared to those with low or high ionized calcium levels (P = 0.004, P = 0.003).

The effectiveness of diltiazem in treating AFib with RVR was highest when patients had normal ionized calcium levels. The study highlighted the importance of considering serum ionized calcium levels when selecting medications for patients with AFib and RVR, providing valuable insights for clinicians in their treatment decisions.

Source: sciencedirect.com/science/article/abs/pii/S0735675723003030