From the Guidelines
For someone with a heart rate of 115-120 beats per minute who cannot take propranolol, alternative beta-blockers like metoprolol or calcium channel blockers such as diltiazem or verapamil are effective options for heart rate control, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. When considering alternative treatments, it's essential to evaluate the patient's specific condition and contraindications.
- Beta-blockers like metoprolol (starting at 25-50 mg twice daily) or atenolol (25-50 mg once daily) can be considered if the patient is not contraindicated to this class of medications.
- Calcium channel blockers such as diltiazem (120-360 mg daily in divided doses) or verapamil (120-360 mg daily in divided doses) are effective options for heart rate control, as supported by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.
- For patients with heart failure, digoxin (0.125-0.25 mg daily) might be appropriate, but non-dihydropyridine calcium channel blockers should be avoided in heart failure with reduced ejection fraction. The choice of medication depends on the underlying cause of the elevated heart rate and the patient's specific contraindications.
- These medications work by slowing electrical conduction through the heart and reducing the influence of the sympathetic nervous system. Before starting any medication, it's essential to identify and address any underlying causes of tachycardia, such as anxiety, dehydration, anemia, hyperthyroidism, or infection.
- According to the 2015 ACC/AHA/HRS guideline, oral verapamil or diltiazem is recommended for ongoing management in patients with AVNRT who are not candidates for, or prefer not to undergo, catheter ablation 1.
From the Research
Alternative Options to Propranolol
If someone has a heart rate of 115 to 120 beats per minute and cannot take propranolol, there are other options available.
- Ivabradine is a selective and specific I(f) inhibitor that acts on the pacemaker activity of sinoatrial node cells, reducing heart rate without compromising hemodynamics 2, 3.
- Metoprolol succinate is another beta-blocker that can be used to reduce heart rate, although it may have more side effects than ivabradine 2.
- Other beta-blockers, such as carvedilol, can also be used, but the dose-dependent association between beta-blocker therapy and risk of outcome should be considered 4.
Considerations for Switching Beta-Blockers
When switching between beta-blockers, it is essential to consider the clinical benefits and potential side effects of each agent 5.
- The development or worsening of chronic noncardiac diseases, new cardiac-related disease, or practical/safety issues may require switching to an alternate agent.
- Guidelines on how to best switch to a different beta-blocker are lacking, but a practical approach can be taken by considering drug interchangeability, rationale for switching, and necessary initial adjustments to dose/frequency 5.
Heart Rate Reduction Strategies
Heart rate reduction can be achieved through various pharmacological strategies, including beta-blockers, calcium antagonists, and ivabradine 3.
- Ivabradine has demonstrated dose-dependent anti-ischemic and antianginal effects in placebo-controlled studies and may be beneficial for patients with contraindications or intolerance to beta-blockers 3.