Propranolol decreases tachycardia and improves symptoms in the Postural Tachycardia Syndrome (POTS): Less is More

Background—Postural Tachycardia Syndrome (POTS) induces disabling chronic orthostatic intolerance with an excessive increase in heart rate (HR) upon standing. Beta-blockade is an appealing treatment approach, but there are conflicting preliminary reports. We tested the hypothesis that propranolol will attenuate the tachycardia and improve symptom burden in patients with POTS. In Protocol #1, a low dose (20mg) was compared to placebo, and the dose response was assessed in Protocol #2. Methods and Results—In Protocol #1, patients with POTS (n=54) underwent acute drug trials of propranolol 20 mg orally and placebo, on separate mornings, in a randomized crossover design. Blood pressure, HR and symptoms were assessed while seated and after standing for up to 10 minutes prior to, and hourly, following study drug. Supine (P<0.001) and standing (P<0.001) HR were significantly lower following propranolol compared to placebo. The symptom burden improvement from baseline to 2 hours was greater with propranolol than placebo (median: −4.5 arbitrary units [au] vs. 0 au; P=0.044). In Protocol #2, 18 patients with POTS underwent similar trials of high dose (80 mg) vs. low dose (20 mg) propranolol. Although high dose elicited a greater decrease than low dose on standing HR (P<0.001) and orthostatic tachycardia (P<0.001), the improvement in symptoms at 2 hours was greater with low dose propranolol (−6 au vs. −2 au; P=0.041). Conclusions—Low dose oral propranolol significantly attenuated tachycardia and improved symptoms in POTS. Higher dose propranolol did not further improve, and may worsen, symptoms.