A 66-year-old gentleman comes for a follow-up clinic visit. He had suffered a myocardial infarction (MI) and underwent primary coronary intervention (PCI) two years ago. He completed cardiac rehabilitation and is currently asymptomatic. His other past medical history includes hypertension and hyperlipidemia. His current medications include aspirin 81 mg daily, metoprolol tartate 12.5 mg twice a day, lisinopril 20 mg daily, and atorvastatin 80 mg daily. His vitals today are as follows: heart rate 80 bpm, blood pressure (BP) 136/88 mm Hg, respiratory rate 16 per min., and oxygen saturation of 96% on room air. His physical exam is otherwise unremarkable. His electrocardiogram (ECG) shows normal sinus rhythm with Q waves in inferior leads. Transthoracic echocardiogram six months ago showed normal regional and global systolic function. Laboratory data are unremarkable, with normal hemoglobin, potassium and creatinine.
Which of the following medication changes would you recommend in this clinic visit?
The correct answer is: D. Increase metoprolol.
Beta-blockers are the first-line therapy to reduce angina and improve exercise tolerance. They decrease the rate–pressure product, atrioventricular nodal conduction and myocardial contractility, which reduces the myocardial oxygen demand. Beta-blockers are the only antianginal drugs proven to prevent recurrent MI and decrease mortality in post-MI patients. It is a Class I (Level of Evidence: B) recommendation to start beta-blocker and continue for three years in all patients with normal left ventricular (LV) function after MI.1 Two large studies with 23 years2 and 14.7 years3 of follow-up showed that higher resting heart rate was an independent risk factor for all-cause mortality. Therefore, it is recommended that beta-blocker dose be adjusted to achieve a resting heart rate under 55 to 60 bpm.1 However, no large randomized trials have studied the effects of beta-blockers on cardiac events in patients with stable ischemic heart disease (SIHD), and it is given a weaker recommendation (Class IIB; Level of Evidence: C) to continue beta blocker therapy beyond three years post-MI.1
This patient is two years post-MI, and beta-blocker should, therefore, be continued for at least one more year. Furthermore, abrupt beta-blocker withdrawal should be avoided as it can lead to increased sympathetic activity, which may lead to accelerated angina, MI, or even sudden death. If withdrawal is necessary, beta blockers should be tapered over a one- to three-week period.
All beta-blockers seem to be equally beneficial in SIHD patients. However, use of beta-blockers should be limited to carvedilol, metoprolol succinate, or bisoprolol, among patients with LV systolic dysfunction (EF ≤40%) and prior MI. This patient had normal systolic function, and so there is no indication to switch to carvedilol.
Multiple trials have demonstrated the mortality benefit of aspirin in post-MI and SIHD patients. Therefore, it is a Class I (Level of Evidence: A) to continue daily aspirin 75 to 162 mg indefinitely in the absence of contraindications in patients with SIHD.1 Similarly, angiotensin-converting enzyme inhibitors should be continued in all SIHD patients with hypertension, diabetes mellitus, LV ejection fraction 40% or less, or chronic kidney disease, unless contraindicated (Class IIa, Level of Evidence: A).1 This patient's BP is at goal <140/90 mm Hg, and so there is no current indication to increase lisinopril.
Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College of Physicians, American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol 2012;60:e44-e164.
Jouven X, Empana JP, Schwartz PJ, Desnos M, Courbon D, Ducimetiere P. Heart-rate profile during exercise as a predictor of sudden death. N Engl J Med 2005;352:1951-8.
Diaz A, Bourassa MG, Guertin MC, Tardif JC. Long-term prognostic value of resting heart rate in patients with suspected or proven coronary artery disease. Eur Heart J 2005;26:967-74.