From the Guidelines
Prescribing a beta blocker with diltiazem can be done cautiously, as the combination may be beneficial in certain clinical situations, such as refractory angina or hypertension, but it requires close medical supervision and careful monitoring due to the risk of excessive bradycardia, heart block, and hypotension, as noted in the 2022 study 1.
Key Considerations
- The combination of beta blockers and diltiazem can cause additive or synergistic effects, leading to excessive bradycardia, heart block, and hypotension, which can be detrimental to patients with certain medical comorbidities, such as heart failure with reduced ejection fraction 1.
- However, in some cases, the combination may be necessary to control symptoms, and the risk of adverse effects can be mitigated with careful dose titration, regular monitoring, and patient education, as suggested by the 2022 study 1.
- The NORDIL study, mentioned in the 2022 study 1, found that the combination of beta blockers and diltiazem did not cause severe bradycardia or cardiac arrest in approximately 700 patients, but it is essential to consider the individual patient's medical history and comorbidities before initiating combination therapy.
Clinical Implications
- When prescribing a beta blocker with diltiazem, it is crucial to carefully evaluate the patient's medical history, including the presence of heart failure, and to monitor their heart rate, blood pressure, and ECG regularly, as recommended by the 2022 study 1.
- Patients should be educated about the potential risks and benefits of combination therapy and should be instructed to seek immediate medical attention if they experience symptoms such as dizziness, unusual fatigue, shortness of breath, or fainting, as noted in the example answer.
- Alternative medication combinations should be considered whenever possible to avoid the potentially dangerous interaction between beta blockers and diltiazem, as suggested by the example answer.
From the FDA Drug Label
Concomitant use of diltiazem with beta-blockers or digitalis may result in additive effects on cardiac conduction. Experience with the use of diltiazem hydrochloride alone or in combination with beta-blockers in patients with impaired ventricular function is very limited. Caution should be exercised when using the drug in such patients.
The use of a beta blocker with diltiazem (Cardizem) may result in additive effects on cardiac conduction. Due to the potential for increased risk of cardiac conduction abnormalities, caution should be exercised when prescribing this combination, especially in patients with impaired ventricular function. It is recommended to use this combination with caution and closely monitor the patient's cardiac function 2.
From the Research
Safety of Prescribing Beta Blocker with Diltiazem
- The combination of diltiazem and beta-blocker therapy may enhance therapeutic benefits in patients with hypertension or coronary heart disease, but it also increases the risk of adverse effects, particularly in patients with left ventricular dysfunction or latent cardiac conduction deficits 3.
- Concomitant use of diltiazem and beta-adrenergic blockers may potentiate bradycardia or atrio-ventricular block, especially in patients with poor left ventricular function or those taking digitalis preparations 4.
- Patients on combination therapy with diltiazem and beta-blockers should be closely monitored for blood pressure, heart rate, and atrioventricular conduction on ECG, and dosage adjustments may be necessary, especially in patients with impaired renal function 3.
- Clinical studies have shown that the combination of diltiazem and beta-blockers can be effective in treating angina pectoris, but precautions should be taken to avoid significant conduction disturbances, even in hypertensive populations 3, 5.
- Diltiazem can be an effective and safe antihypertensive drug, alone or in combination with other agents, including beta-blockers, but careful consideration of the potential risks and benefits is necessary 6.