C spasm has been reported to be related to syncope and sudden death.1 The head-up tilt test is known as a useful method in the evaluation of syncope of unknown origin.2 No report has shown that the tilt test can provoke coronary spasm. We present 3 cases in which coronary spasm was induced during an isoproterenol tilt-table test and discuss the mechanism. • • • CASE 1: A 47-year-old man was admitted for workup of recurrent syncope, which followed chest tightness in the early morning. Physical examination, resting 12lead electrocardiogram, chest xray, echocardiogram, and biochemistry were normal. Exercise stress testing did not provoke an ischemic response and his coronary angiogram showed normal coronary arteries. Then, a tilt test was performed with an isoproterenol infusion at doses of 1, 2, and 3 mg/min at each stage including supine and 70° head-up tilt for 6 minutes. The baseline heart rate was 59 beats/min. After progressively increasing the dose of isoproterenol to 3 mg/min for 6 minutes, his heart rate increased a little to 61 beats/ min with a blood pressure of 96/48 mm Hg. Five minutes after head upright tilting with a 3 mg/min isoproterenol infusion, blood pressure and heart rate increased to 109/54 mm Hg and to 90 beats/min respectively, and meanwhile, a progressive elevation in the ST segment in multiple leads was also noted (Figure 1). The initial ST-segment elevation was found in leads II, III, and aVF, subsequently shifting to leads I, aVL, and precordial leads V1 to V6. Thereafter, chest tightness developed with marked hypotension (blood pressure 58/34 mm Hg). These conditions resolved after lying down and after sublingual nitroglycerin was administered. Electrocardiographic abnormalities returned to normal completely after 24 hours. Holter monitoring documented transient ST-segment elevation with nonsustained ventricular tachycardia at 1:30 A.M. (Figure 2). After treatment with nifedipine and isosorbide nitrate, this patient was free of chest pain and syncope, and no more ST-segment changes were induced by repeat tilt test. CASE 2: A 65-year-old man had 4 episodes of near syncope following typical chest discomfort in the morning. Resting electrocardiogram and coronary angiogram were normal. A tilt test were performed with a blood pressure of 115/85 mm Hg and a heart rate of 78 beats/min at baseline. During From the Cardiology Section, Department of Medicine, Chang Gung Medical College, Chang Gung Memorial Hospital, Keelung, Taiwan. Dr. Cherng’s address is: Chang Gung Memorial Hospital, 222 Mai Chin Road, Keelung, Taiwan. Manuscript received June 12, 1997; revised manuscript received and accepted September 5, 1997. FIGURE 1. Twelve-lead electrocardiogram (Case 1) showing ST-segment elevation in leads II, III, and aVF after a 5-minute head-up tilt with an isoproterenol infusion at a rate of 3 mg/min. ST elevation migrated to leads I, aVL, and V1 to V6 8 minutes later with complete resolution after 24 hours.