Pearls of Wisdom: Targeting Exercise Heart Rate Without A Treadmill
Joshua is a 54-year-old male patient with mild residual symptoms of angina with exercise, sexual activity, and sometimes postprandially. His resting heart rate on metoprolol tartrate 50 mg (twice a day) was 68, down from a pre-treatment rate of 80-84.
Having recently reviewed a similar case, you know to try to maximize beta blockade, so you suggested increasing the metoprolol to target an exercise heart rate <125 bpm. Unfortunately, you do not have a treadmill apparatus in your office, and the patient does not have health insurance.
A visit to a cardiologist with a treadmill will cost hundreds of dollars or more. Is there a simple office test a clinician might employ to ascertain the adequacy of beta blockade upon exercise heart rate without resorting to formal treadmill testing?
A. No, a treadmill is the only way to assess exercise heart rate
B. Yes: use oral pseudoephedrine 120 mg PO single dose to stimulate tachycardia
C. Yes: use methylphenidate 20 mg PO single dose to stimulate tachycardia
D. Yes: use the office squat test to stimulate tachycardia
What is the correct answer?
(Answer and discussion on next page)
Louis Kuritzky, MD, has been involved in medical education since the 1970s. Drawing upon years of clinical experience, he has crafted each year for almost 3 decades a collection of items that are often underappreciated by clinicians, yet important for patients. His “Pearls of Wisdom” as we like to call them, have been shared with primary care physicians annually in an educational presentation entitled 5TIWIKLY (“5 Things I Wish I Knew Last Year”…. or the grammatically correct, “5 Things I Wish I’d Known Last Year”).
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Answer: Use the office squat test to stimulate tachycardia
Beta-blockers, such as metoprolol, are commonly chosen as first line treatment for angina. Most patients prefer the simplicity of once-daily dosing, but generic short acting twice-daily metoprolol (previously sold under the trade name “Lopressor”) has been substantially less expensive than the once daily long acting metoprolol.
(Note: If you’re trying to figure out a way to remember which metoprolol is which, the shorter word (metoprolol tartrate), is the shorter acting drug (twice daily) and the longer word (metoprolol succinate) is the longer acting drug (once daily).
We are trying to do our patient the good service of obtaining maximum benefit from the medication that he is already taking by titrating it to exercise heart rate. How might we do this without the benefit of a treadmill?
The Research
Dr. Stephen Glasser has published a simple maneuver that may be useful when economic or logistical constraints preclude exercise treadmill testing.1
He reported that you must simply ask a patient to perform as many squats as possible within 60 seconds, and measure the heart rate in the last 5 seconds. If the heart rate exceeds 120 bpm, the patient has not reached maximal beta blockade.
If the squat testing is used to assess exercise heart rate, his article suggests titrating the heart rate during the squat test to 100-110 bpm.
While sophisticated testing methodologies are often preferred, not all patients have access to such interventions. This literature suggests that a simple office exercise maneuver, the 60-second office squat test—for patients with sufficient mobility to perform it—may help us assess the degree of beta blockade.
Reference:
1. Glasser SP. Currently Recommended Drug Therapy for Persistent Angina. Contemporary Internal Medicine. 1992;5:17-25.