Head Up Tilt Table testing (HUTT) is often associated with a lengthy two-staged protocol (with and without isoproterenol). Recently, Shen and colleagues described a single-stage isoproterenol HUTT.1 The purpose of this study was to compare the introduction of this single-stage tilt protocol to sequential two-staged tilt table testing. Patients with recurrent or dramatic syncope or near syncope were referred for HUTT. Informed consent was obtained from all patients prior to the study, which was performed in the post-absorptive state. Prior to July 9, 2000, HUTT was performed using a two-staged tilt protocol as follows: a 60° passive tilt for 30 minutes and, if negative, followed by a 10-minute tilt with isoproterenol titration to a 20% heart rate increase (two-staged HUTT). On July 9, 2000, the Cardiology Division at Winthrop University Hospital converted to a single stage isoproterenol protocol for all operators as described by Shen and coworkers.1 This protocol consisted of a 10-minute, 70° tilt with a fixed dose isoproterenol infusion (0.05 mg/kg/minute). Patients with isoproterenol contraindications underwent passive tilt (40 minutes for conventional two-staged 60° tilt, and 45 minutes for single-staged 70° tilt. Patients on beta-blockers, orthostatic hypotension, significant anemia, and endocrinologic abnormalities, such as diabetes, hypoglycemia, or thyroid dysfunction, were excluded from the study. Also, patients with abnormal findings during electrophysiologic testing (such as carotid sinus hypersensitivity, sinus node dysfunction, atrioventricular conduction system disease or sustained ventricular arrhythmias) were also excluded. One hundred consecutive patients prior to July 9, 2000, using two-staged sequential tilts were compared to the first one hundred consecutive patients who received the single-stage protocol. The results of these tests were compared using a Chi-square statistical analysis; p
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