Contraindication of Verapamil and Diltiazem in Heart Failure with Irregular Rhythm

Mechanism of Action and Negative Effects

Non-dihydropyridine calcium channel blockers, such as verapamil and diltiazem, inhibit calcium influx through L-type calcium channels in the myocardium, reducing myocardial contractility and potentially depressing already compromised ventricular function in heart failure patients, as stated by the European Society of Cardiology and the American Heart Association 1, 2
These agents have pronounced effects on myocardial contractility as well as cardiac pacemaker and atrioventricular conduction cells, leading to negative inotropic and chronotropic effects that can be detrimental in heart failure, according to the American College of Cardiology 2

Both diltiazem and verapamil should be avoided in patients with systolic heart failure, as stated in guidelines from the American Heart Association and the European Society of Cardiology 1, 3, 4
In atrial fibrillation with heart failure, these agents can exacerbate heart failure symptoms due to their negative inotropic effects, as reported by the American College of Cardiology 5

In atrial fibrillation, the rapid ventricular response can compromise cardiac output by loss of atrial enhancement of ventricular filling, rapid heart rate increasing demand and decreasing coronary perfusion, and rapidity of ventricular response diminishing cardiac contraction and relaxation, as described by the American Heart Association 5
Adding a negative inotropic agent like verapamil or diltiazem to this scenario can precipitate hemodynamic collapse in patients with compromised left ventricular function, according to the American College of Cardiology 6, 7

Beta-blockers are preferred for rate control in heart failure patients with atrial fibrillation due to their favorable effects on the natural history of heart failure, as recommended by the American College of Cardiology and the European Society of Cardiology 5
Digoxin can be used in combination with beta-blockers for more effective rate control, especially during exercise, as stated by the American Heart Association 5

The contraindication of verapamil and diltiazem is strongest for patients with systolic heart failure (reduced ejection fraction), as emphasized by the European Society of Cardiology 1, 4
Calcium channel blockers like amlodipine or felodipine (dihydropyridines) have neutral effects on survival and may be considered for concomitant hypertension or angina in heart failure patients, according to the European Society of Cardiology 1
When treating supraventricular tachyarrhythmias in patients without heart failure, verapamil and diltiazem can be effective and safe options, as reported by the American College of Cardiology and the American Heart Association 3, 8
Always verify the absence of pre-excited atrial fibrillation before administering diltiazem or verapamil, as these drugs can precipitate ventricular fibrillation in patients with accessory pathways, as warned by the American College of Cardiology and the American Heart Association 3, 7