AMI was documented on the basis of typical chest pain lasting > 30 min, elevated serum creatine kinase and MB subform levels at least twice the normal value, and an elevated ST-segment > 1.0 mm in more than two contiguous limb leads or > 2.0 mm in more than two contiguous precordial leads, respectively. Peripheral arterial disease was defined by duplex and color Doppler ultrasonography in patients with either claudication or a nonhealing lower extremity ulcer. Congestive heart failure was evaluated before discharge according to the New York Heart Association (NYHA) classification. Patients with previous myocardial infarction, severe valvular heart disease, nonsinus rhythm, history of percutaneous coronary angioplasty, bypass surgery, NYHA functional class IV, or poor echocardiographic image quality were excluded from the study. in detail
Dobutamine Stress Test
DSE was performed 14 ± 8 days after AMI using an echocardiographic system (Sonos 2500; Hewlett-Packard; Andover, MA) with a 2.5 MHz transducer, and was digitized online using TomTec Integrated Cardiac Analysis Software (Tom Tec Imaging Systems; Boulder, CO). All cardioactive drugs were withdrawn at least five half-lives before DSE. With the patient reclining in the left lateral decubitus position, baseline hemodynamic, ECG, and echocardiographic data were collected. Dobutamine was then infused into a peripheral vein using an incremental regimen of 5, 10, 20, 30, and 40 ^g/kg/min (3 min/dose). IV atropine (0.5 to 1.0 mg) was added if patients did not achieve 85% of their age-predicted maximal heart rate and had no symptoms or signs of ischemia. Two-dimensional echocardiograhic images in the four standard views were continuously acquired during each dose of dobutamine infusion and for at least 5 min after the end of the infusion. Images were recorded in a quadscreen format and stored on an optic disk for analysis. BP, heart rate, and ECGs were monitored throughout the study. End points included achievement of peak stress, development of severe ischemia, ST-segment elevation, hypertension (systolic BP > 230 mm Hg), significant arrhythmia, or any severe complication.