Diltiazem Contraindication in Atrial Fibrillation Based on Ejection Fraction
Diltiazem is contraindicated for treatment of atrial fibrillation when the left ventricular ejection fraction (LVEF) is less than 40%. 1, 2
Guideline-Based Ejection Fraction Thresholds
The European Society of Cardiology (ESC) 2016 guidelines explicitly state that verapamil is contraindicated in LV failure with pulmonary congestion or LVEF <40%, and this same threshold applies to diltiazem as both are non-dihydropyridine calcium channel blockers with similar negative inotropic effects. 1
The ACC/AHA/ESC guidelines consistently warn that in patients with decompensated heart failure and atrial fibrillation, intravenous administration of a nondihydropyridine calcium channel antagonist may exacerbate hemodynamic compromise and is not recommended (Class III recommendation). 1
Clinical Reasoning for the 40% Cutoff
Beta-blockers should be used as first-line agents when LVEF is <40% or signs of congestive heart failure are present, using the smallest dose necessary to achieve rate control. 1, 2
Diltiazem and verapamil should be avoided in patients with reduced LV ejection fraction or heart failure due to their negative inotropic effects, which can worsen hemodynamic status. 1, 2
Amiodarone is the alternative option for patients with hemodynamic instability or severely reduced LVEF who cannot tolerate beta-blockers. 1, 2
Additional Contraindications Beyond Ejection Fraction
Beyond the LVEF <40% threshold, diltiazem is also contraindicated in: 1
- Decompensated systolic heart failure regardless of specific ejection fraction number
- AV block greater than first degree or SA node dysfunction (without pacemaker)
- Hypotension or cardiogenic shock
- WPW syndrome with atrial fibrillation/flutter (may paradoxically accelerate ventricular response)
Common Pitfalls to Avoid
The most critical error is using diltiazem in patients with LVEF <40% despite its effectiveness in rate control, as this can precipitate acute decompensation. 2 Even though some retrospective studies suggest diltiazem may be tolerated in select patients with reduced ejection fraction, guideline recommendations prioritize safety and explicitly contraindicate its use below the 40% threshold. 3, 4, 5
Do not confuse "heart failure with preserved ejection fraction" (HFpEF, typically LVEF ≥50%) with reduced ejection fraction—diltiazem can be used cautiously in HFpEF but remains contraindicated when LVEF <40%. 4
Always verify a recent echocardiogram before administering diltiazem for atrial fibrillation, as patients may have undiagnosed reduced ejection fraction. 2