As we continue our experience with deprescribing medications, particularly with proton pump inhibitors, benzodiazepines, or chronic opioids, another drug class that is worth reviewing is beta blocker in the context of Post MI management.

Many years ago, we used to counsel patients that they would require to take their beta blockers for the rest of their lives after having a heart attack. This was well supported with clinical evidence at the time.  However, time has changed and technologies have advanced. The current reperfusion technology has improved greatly, such that the role of indefinitely therapy with beta blocker has been called into question.

American College of Cardiology has written an article summarizing the evidence around the use of beta blockers in post MI management.  Here’s a link to the article.

The game changer appears to be stimulated from a recent meta-analysis conducted by Bangalore S et al, published in the American Journal of Medicine in 2014.

Here’s a link to this article and the highlights from the study as below:

  • This was a meta-analysis of randomized trails evaluating beta blockers in myocardial infarction enrolling at least 100 patients
  • The primary outcome was all-cause mortality.
  • The analysis was performed stratifying studies into:
    • Reperfusion-era which was defined as having 50% undergoing reperfusion or receiving aspirin / statin, or
    • Pre-reperfusion era.
  • Results:
    • 60 trials with 102003 patients met the inclusion criteria
    • In the pre-reperfusion era, beta blockers reduced cardiovascular mortality (IRR 0.87; 95% CI, 0.78-0.98).  Other benefits include reduction in myocardial infarction (IRR 0.78; 95% CI, 0.62-0.97), and angina (IRR 0.88; 95% CI, 0.82-0.95), with no difference for other outcomes.
    • In the reperfusion era, the incidence rate ratio in cardiovascular mortality was not significant. (IRR 1.00; 95% CI, 0.91-1.09).
      • The use of beta-blockers has demonstrated reduction in myocardial infarction (IRR 0.72; 95% CI, 0.62-0.83) (number needed to treat to benefit [NNTB] = 209) and angina (IRR 0.80; 95% CI, 0.65-0.98) (NNT = 26). However, there was an increase in heart failure (IRR 1.10; 95% CI, 1.05-1.16) (number needed to treat to harm [NNTH] =79), cardiogenic shock (IRR 1.29; 95% CI, 1.18-1.41) (NNTH =90), and drug discontinuation (IRR 1.64; 95% CI, 1.55-1.73), with no benefit for other outcomes.  
      • The authors also noted the benefits of beta blockers for recurrent myocardial infarction and angina in the reperfusion era appeared to be short term (30 days)
Figure 2 Beta blockers vs controls for the outcome of all-cause mortality in acute myocardial trails The American Journal of Medicine (2014) 127, 939-953

While many guidelines continue to recommend continuing beta blocker therapy as part of Post MI management, it appears, at least from recent evidence, that a subset of post MI patients who have had the event during this reperfusion era to consider discontinuing beta blockers after taking them for few years (e.g. 3 years).  This is only applicable if there is no evidence of LV systolic dysfunction or other indications (e.g. atrial fibrillation).

This area is likely a controversial topic and many clinicians may not be on the same page about discontinuing beta blocker therapies. However if it is deemed reasonable to discontinue (e.g. intolerable side effects such as fatigue, bradycardia), here are some practical points to keep in mind:

  • Beta blockers should never be abruptly discontinued. Stopping beta blocker abruptly is like taking the brake off an accelerating car – it can be dangerous.
  • Instead, a tapering plan should be implemented by reducing the dose by ~25% weekly (or as reasonable based on dosage strength availability).
  • For Metoprolol:
    • Metoprolol 50mg po BID x 1 week
    • Metoprolol 37.5mg po BID x 1 week
    • Metoprolol 25mg po BID x 1 week
    • Metoprolol 12.5mg po BID x 1 week, then stop
  • For Bisoprolol:
    • Bisoprolol 10mg po daily x 1 week
    • Bisoprolol 7.5mg po daily x 1 week
    • Bisoprolol 5mg po daily x 1 week
    • Bisoprolol 2.5mg po daily x 1 week, then stop
  • For frail individuals, the tapering period may need to be extended.
  • Note that sustained release metoprolol tablet should not be cut in half
  • When beta blockers are stopped, the beta blocker receptors may overexpress, leading to overstimulation with norepinephrine. Common symptoms to watch for include anxiety, sweating, hypertension and angina or related symptoms.

If you have a patient who may need to taper off beta blocker due to lack of benefits or intolerable side effects, I hope this post has offered some helpful tips.  Thank you for reading my post!