What is the role of Cardizem (Diltiazem) in managing atrial fibrillation with rapid ventricular response (RVR) in the presence of congestive heart failure (CHF)?

From the Guidelines

Cardizem (diltiazem) should be avoided in atrial fibrillation with rapid ventricular response (AFib with RVR) when congestive heart failure (CHF) is present, due to its negative inotropic effects that can worsen heart failure. According to the 2024 ESC guidelines for the management of atrial fibrillation 1, beta-blockers are recommended as first-choice drugs in patients with AF and LVEF >40% to control heart rate and reduce symptoms. However, in patients with AF and LVEF ≤40%, beta-blockers and/or digoxin are recommended to control heart rate and reduce symptoms.

In the context of CHF, the use of diltiazem can be problematic due to its potential to depress myocardial function and increase the risk of heart failure, as noted in the 2005 ACC/AHA guideline update for the diagnosis and management of chronic heart failure in the adult 1. Therefore, beta-blockers like metoprolol are generally preferred for rate control in this scenario, starting at 5 mg IV, potentially followed by oral dosing at 25-100 mg twice daily. If beta-blockers cannot be used, amiodarone (150 mg IV over 10 minutes, followed by 1 mg/min infusion for 6 hours, then 0.5 mg/min) may be considered as it has less negative inotropic effect, as suggested in the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.

For patients with severely decompensated heart failure and AFib with RVR, immediate cardioversion may be necessary rather than medication. The underlying heart failure should be treated concurrently with diuretics, ACE inhibitors/ARBs, and other appropriate heart failure therapies. This approach addresses both the arrhythmia and the underlying cardiac dysfunction, which are often interrelated, as AFib can worsen heart failure and heart failure can promote AFib.

Key considerations in managing AFib with RVR in the presence of CHF include:

• Avoiding medications that can worsen heart failure, such as diltiazem
• Using beta-blockers as first-line therapy for rate control
• Considering amiodarone as an alternative when beta-blockers are contraindicated
• Treating the underlying heart failure with appropriate therapies
• Evaluating the need for immediate cardioversion in severely decompensated patients.

From the FDA Drug Label

Diltiazem slows the ventricular rate in patients with a rapid ventricular response during atrial fibrillation or atrial flutter In a limited number of studies of patients with compromised myocardium (severe congestive heart failure, acute myocardial infarction, hypertrophic cardiomyopathy), administration of intravenous diltiazem produced no significant effect on contractility, left ventricular end diastolic pressure, or pulmonary capillary wedge pressure However, in rare instances, worsening of congestive heart failure has been reported in patients with preexisting impaired ventricular function The use of diltiazem hydrochloride injection or diltiazem hydrochloride for injection should be undertaken with caution when the patient is compromised hemodynamically or is taking other drugs that decrease any or all of the following: peripheral resistance, myocardial filling, myocardial contractility, or electrical impulse propagation in the myocardium

Cardizem (diltiazem) can be used for atrial fibrillation with rapid ventricular response (RVR) in the presence of congestive heart failure (CHF), but it should be used with caution due to the potential risk of worsening CHF in patients with preexisting impaired ventricular function 2, 2.

• Key considerations:
  • Monitor patient hemodynamics closely
  • Be aware of potential interactions with other medications
  • Have emergency equipment readily available
• Main goal: slow the ventricular rate in patients with atrial fibrillation or atrial flutter.

From the Research

Cardizem for Afib RVR with Presence of CHF

• The use of Cardizem (diltiazem) for atrial fibrillation (Afib) with rapid ventricular response (RVR) in patients with congestive heart failure (CHF) has been studied in several research papers 3, 4, 5, 6, 7.
• According to a study published in 2022, diltiazem was found to be effective in controlling heart rate in patients with Afib and CHF, with similar safety outcomes compared to metoprolol 3.
• Another study published in 2022 found that diltiazem reduced heart rate more quickly and reduced heart rate by 20% or greater more frequently than metoprolol in patients with Afib and CHF, with no differences in safety outcomes 3.
• However, a study published in 2022 also found that diltiazem was associated with a higher incidence of worsening heart failure symptoms in patients with heart failure with reduced ejection fraction (HFrEF) 4.
• A review of studies published in 2022 found that diltiazem likely achieves rate control faster than metoprolol, though both agents seem safe and effective for rate control in patients with Afib and RVR 5.
• An older study published in 1994 found that intravenous beta blockers and calcium channel blockers, including diltiazem, were equally effective in rapidly controlling the ventricular rate in acute Afib 6.
• A study published in 2019 found that diltiazem achieved similar rate control with no increase in adverse events compared to metoprolol in patients with HFrEF and Afib with RVR 7.

Key Findings

• Diltiazem is effective in controlling heart rate in patients with Afib and CHF 3, 7.
• Diltiazem may reduce heart rate more quickly and reduce heart rate by 20% or greater more frequently than metoprolol in patients with Afib and CHF 3.
• Diltiazem may be associated with a higher incidence of worsening heart failure symptoms in patients with HFrEF 4.
• Both diltiazem and metoprolol seem safe and effective for rate control in patients with Afib and RVR 5.