Pellikka P (Mayo Clinic), Lee CY (Singapore Heart Centre), Seward JB (Mayo). Circ. Suppl. #96, Abstr 196. Am. Heart Assoc, 1997.  Transthoracic stress echocardiography performed with a transesophageal atrial pacing (TAP) catheter has been proposed as an alternative method of stress echocardiography. In this prospective study, patients (pts) underwent both TAP and dobutamine stress echocardiography (DSE). We compared the tests' safety, patient tolerance, duration, hemodynamics and concordance in inducing wall motion abnormality (WMA). Methods: Pts underwent DSE and TAP consecutively and randomly on the same day. TAP was performed using a bipolar pacing and recording catheter in a flexible 18 Fr Sheath (CardioCommand). Pacing was initiated at 10 beats/min above resting heart rate and increased 20 beats/min every 2 mins until target heart rate or another endpoint was reached. DSE was performed using a standard protocol. DSE and TAP results were read blindly. Pts graded both tests for comfort and acceptability. Rest and peak cardiac output were assessed by Doppler during DSE and TAP. Results: TAP was feasible in 100 of 104 pts (96%). TAP studies were significantly shorter 8.5+/- 3.6 vs 31+/- 9 min, p < .0001) and were associated with less symptoms, dysrrhythmias, and hypertensive or hypotensive endpoints. Target heart rate was more often achieved with TAP (94% vs 82%, p < .0001). No complications occurred with either test; mean acceptability scores were similar. Mean cardiac output at peak stress was greater with DSE (10.4 +/- 2.8 vs 8.6 +/- 8.25 l/min, p < .0001). There was good concordance of wall motion changes between DSE and TAP, examined in 2 ways: (1) Presence of inducible WMA (kappa-0.71); (2) Diagnosis summary (normal ischemia, infarct, or peri-infarct ischemia) in each coronary artery distribution (kappa for LAD=0.72, RCA=0.74, LCX=0.65). Order of tests did not affect concordance of results. Conclusions: Transesophageal is comparable to DSE for the diagnosis of ischemic heart disease. TAP is safe and well tolerated. The principle advantages of TAP are reduced time and effort of the procedure.