Is Cardizem (diltiazem) safe to use for hypertension and tachycardia in patients with an ejection fraction of 40-45%?

Diltiazem Should Not Be Used for Hypertension and Tachycardia in Patients with EF 40-45%

Diltiazem (Cardizem) is contraindicated for patients with heart failure with reduced ejection fraction (HFrEF), including those with an ejection fraction of 40-45%, due to its negative inotropic effects that can worsen heart failure.

Classification of Heart Failure by Ejection Fraction

An ejection fraction of 40-45% falls into the category of heart failure with reduced ejection fraction (HFrEF) or heart failure with mildly reduced ejection fraction (HFmrEF):

• HFrEF: LVEF ≤40% 1
• HFmrEF: LVEF 41-49% 1

A patient with an EF of 40-45% should be treated according to guidelines for heart failure with reduced ejection fraction.

Contraindication of Diltiazem in HFrEF

The 2015 American Heart Association scientific statement on treatment of hypertension in patients with coronary artery disease explicitly states:

• "Drugs to avoid in patients with hypertension and HF with reduced ejection fraction are nondihydropyridine CCBs (such as verapamil and diltiazem), clonidine, moxonidine, and hydralazine without a nitrate (Class III Harm; Level of Evidence C)" 1

This is a Class III Harm recommendation, meaning the intervention is potentially harmful and should not be performed.

Recommended Alternatives for Rate Control

For patients with atrial fibrillation and heart failure with reduced ejection fraction who need rate control:

1. First-line options:

   • Intravenous digoxin or amiodarone (Class I recommendation) 1
   • Oral digoxin for heart rate control at rest (Class I recommendation) 1

2. For hypertension management in HFrEF:

   • ACE inhibitors or ARBs (Class I recommendation) 1
   • Beta-blockers (carvedilol, metoprolol succinate, bisoprolol, or nebivolol) (Class I recommendation) 1
   • Aldosterone receptor antagonists (Class I recommendation) 1
   • Thiazide or thiazide-type diuretics for BP control 1

Risks of Diltiazem in Reduced EF

Diltiazem carries significant risks in patients with reduced ejection fraction:

• Negative inotropic effects that can worsen heart failure 2
• Risk of cardiac conduction abnormalities, particularly when combined with beta-blockers 2, 3
• Higher incidence of worsening heart failure in patients with reduced EF (17% vs 4.8% in preserved EF) 4

Special Considerations

While some older research suggests potential benefits of diltiazem in selected heart failure patients 5, 6, these studies are limited and outdated. Current guidelines clearly recommend against using diltiazem in patients with reduced ejection fraction.

If rate control for atrial fibrillation is needed in this population:

• Digoxin is preferred for patients with HF and LV dysfunction 1
• Amiodarone is recommended when other measures are unsuccessful 1
• Beta-blockers should be used with caution and appropriate monitoring 1

Conclusion

For a patient with hypertension, tachycardia, and an ejection fraction of 40-45%, diltiazem should be avoided due to the risk of worsening heart failure. Instead, use guideline-directed medical therapy including ACE inhibitors/ARBs, beta-blockers, aldosterone antagonists, and diuretics for hypertension management, and digoxin or amiodarone for rate control if needed.