by Najm Haque, PGY2
Atrial fibrillation with rapid ventricular response is a common emergency room problem. Patient with stable blood pressure who present in Afib with RVR need medications to control their heart rate (unstable patients require more cardioversion). Traditionally, these patients receive beta blockers or calcium channel blockers in IV form for rate control. The most common medications used in the US are metoprolol and diltiazem, but it is unclear which is superior.
Fromm et al Diltiazem vs. Metoprolol in the Management of Atrial Fibrillation or Flutter with Rapid Ventricular Rate in the Emergency Department
This study was published in the Journal of Emergency Medicine in April 2015 and compared how fast rate control was achieved in diltiazem vs metoprolol. This was a prospective, double-blind study which compared the effects of both medications at 30 minutes, as well as looking at mean decrease in heart rate, and adverse effects. Patients were randomized and either received Diltiazem 0.25 mg/kg IVP (maximum dose of 30mg) or Metoprolol 0.15mg/kg IVP (maximum dose of 10mg). A second escalation dose of 0.35mg/kg of diltiazem (max of 30mg) or 0.15mg/kg of metoprolol (max of 10mg) was given at 15 minutes if target HR was not achieved. The results of the study showed that diltiazem reached the target HR of <100 much more frequently at 5 minutes (50% vs 10.7%) and at 30 minutes (95.8% vs 46.4%) when compared to metoprolol. There was no difference in adverse effects.
Demircan C, Cikriklar HI, Engindeniz Z, et al. Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation.
This study was published in the Journal of Emergency Medicine in 2005. Similar to the study by Fromm et al, this study compared diltiazem (0.25mg/kg, max of 25mg) and metoprolol (0.15mg/kg, max of 10mg), was prospective and randomized, and used a target heart rate < 100. They compared the two medications at intervals of 2, 5, 10, 15, and 20 minutes. In each interval, the success rate of diltiazem was higher than metoprolol, and at 30 minutes 90% of patients receiving diltiazem reached the target heart rate while 80% of patients receiving metoprolol reached the target heart rate. In addition, the decrease in heart rate was higher in the group receiving diltiazem than the group receiving metoprolol.
Scheuermyer FX, Grafstein E, Stenstrom R, et al. Safety and efficiency of calcium channel blockers versus beta-blockers for rate control in patients with atrial fibrillation and no acute underlying medical illness.
This study was published in 2013 and compared the effect of calcium channel blockers and beta blockers in ER patients with known Afib who present with Afib with RVR. The primary outcome of this retrospective cohort study was hospital admissions and patients with underlying medical conditions requiring hospitalization were excluded (which means this study looked for patients who were admitted to the hospital for Afib with RVR and no other medical problem). The study enrolled 259 patients over a 4 year period and noted patients receiving CCBs were more likely to be admitted (31% vs 27%) although this was statistically insignificant. Secondary outcomes were ED length of stay, adverse effects, return visits in 7 or 30 days, and the incidence of stroke or death in 30 days. In all categories, both CCBs and beta blockers were essentially equal.
What do these studies tell us?
The studies by Fromm et al and by Demircan et all are essentially the only two studies published which compare diltiazem and metoprolol directly in an emergency room population. The first of these studies (Demircan) noted that diltiazem was slightly better than metoprolol in achieving a target heart rate while the most recent study by Fromm noted that diltiazem was significantly better than metoprolol. Of note, Fromm did use a higher maximum dose of diltiazem (30mg vs 25mg). Both studies did an adequate job of excluding patients with other conditions which caused the afib with RVR. The third study compared the broad group of CCBs vs beta blockers and concluded there was no difference, but it does not specify which medications were used and it’s primary end point was not heart rate but whether or not a patient was admitted to the hospital. So what should you do in the emergency room? In patients who present with Afib with RVR with no other underlying condition like infection, ingestion, STEMI, it appears diltiazem is more effective than metoprolol in achieving rate control. However, if there is an underlying condition like sepsis, there is currently no published data about what agent should be given.
What about using both?
If a patient is given 2 doses of metoprolol without resolution of rapid ventricular response, the instinct is to give diltiazem to try and achieve better rate control. However, there is a theoretical risk of causing the patient to go into complete heart block if this is done. There are no published case reports of this happening, so the risk is purely theoretical, but the administration of both medications should be avoided.
Demircan C, Cikriklar HI, Engindeniz Z, et al. Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation. Emerg Med J 2005;22(6):411-4. Erratum in: Emerg Med J 2005;22(10):758. PubMed PMID: 15911947.
Scheuermeyer FX, Grafstein E, Stenstrom R, et al. Safety and efficiency of calcium channel blockers versus beta-blockers for rate control in patients with atrial fibrillation and no acute underlying medical illness. Acad Emerg Med 2013;20(3):222-30. PubMed PMID: 23517253.
Fromm C, et al. Diltiazem vs. Metoprolol in the Management of Atrial Fibrillation or Flutter with Rapid Ventricular Rate in the Emergency Department. J Emerg Med. 2015 Apr 22. [Epub ahead of print]