Differential diagnosis of vasovagal syncope: Postural orthostatic tachycardia

Abstract

Postural tachycardia syndrome (POTS) is a syndrome defined as an increase in heart rate (HR) of ≥30 bpm within 10 min of assuming an upright posture in the absence of orthostatic hypotension (decrease in blood pressure (BP) >20/10 mmHg). The prevalence of POTS has been estimated as 500,000—3,000,000 patients in the USA. Because it affects mainly women between 13 and 50 years of age, the impact on productivity at work and lifestyle can be devastating. Considerable clinical overlap exists between POTS and vasovagal syncope (VVS) with patients experiencing similar orthostatic symptoms related to insufficient adaptation to blood volume shifts during upright posture. Nevertheless, differences emerge during head up tilt table testing. In patients with POTS, during upright tilt, sympathetic tone increases, there is an early and sustained tachycardia, and patients complain of presyncope without frank syncope. In contrast, patients with VVS experience delayed symptoms and abrupt drops in BP and HR and are more likely to lose consciousness. Treatment of POTS includes exercise and medications directed at decreasing sympathetic tone or increasing blood volume.