Is Cardizem (Diltiazem) effective for treating chronic right heart failure?

Cardizem (Diltiazem) Is Not Recommended for Chronic Right Heart Failure

Diltiazem (Cardizem) is contraindicated in chronic right heart failure and should not be used for this condition due to its negative inotropic effects that can worsen heart failure outcomes.

Rationale for Avoiding Diltiazem in Heart Failure

The European Society of Cardiology guidelines explicitly state that calcium antagonists, particularly diltiazem and verapamil, are not recommended for the treatment of heart failure caused by systolic dysfunction 1. These non-dihydropyridine calcium channel blockers can worsen heart failure due to their negative inotropic effects on the myocardium.

Diltiazem works by inhibiting calcium influx during membrane depolarization of cardiac and vascular smooth muscle 2. While this mechanism is beneficial for certain cardiovascular conditions like supraventricular tachycardias, it can have detrimental effects in patients with compromised ventricular function.

Preferred Treatment Options for Heart Failure

Instead of diltiazem, guideline-directed medical therapy (GDMT) for heart failure should include:

1. First-line therapy:

   • ACE inhibitors or ARBs at maximum tolerated doses 3
   • Evidence-based beta-blockers (carvedilol, metoprolol succinate, or bisoprolol) 3

2. Additional therapies:

   • Mineralocorticoid receptor antagonists (spironolactone, eplerenone) for patients with LVEF ≤35% 3
   • SGLT2 inhibitors (dapagliflozin, empagliflozin) which reduce heart failure hospitalizations and mortality 3

Limited Evidence for Diltiazem in Heart Failure

While some older, small studies have examined diltiazem in heart failure, they do not override current guideline recommendations:

• A 1984 study showed some hemodynamic improvements with diltiazem in severe heart failure but noted transient junctional arrhythmias in 3 of 8 patients receiving IV diltiazem 4. This small, short-term study does not support long-term use.

• A 1985 review article suggested that diltiazem's relative lack of negative inotropic effects compared to verapamil might allow safer use in heart failure patients, particularly when control of supraventricular arrhythmias is needed 5. However, this theoretical benefit has not translated into guideline recommendations.

Special Considerations

For patients with both atrial fibrillation and heart failure:

• Some limited recent research has examined diltiazem for acute management of atrial fibrillation with rapid ventricular response in heart failure patients 6, 7.
• However, these studies focused on short-term emergency management, not chronic therapy, and do not override guideline recommendations against chronic diltiazem use in heart failure.

Drugs to Avoid in Heart Failure

The European Society of Cardiology specifically lists several drug classes to avoid or use with caution in heart failure, including:

• Non-steroidal anti-inflammatory drugs (NSAIDs) and COX-2 inhibitors
• Class I anti-arrhythmic agents
• Calcium antagonists (verapamil, diltiazem, and short-acting dihydropyridines) 1
• Tricyclic antidepressants
• Corticosteroids
• Lithium

Conclusion

For chronic right heart failure management, follow guideline-directed medical therapy with ACE inhibitors/ARBs, beta-blockers, mineralocorticoid receptor antagonists, and SGLT2 inhibitors. Diltiazem should be avoided due to its potential to worsen heart failure through negative inotropic effects.