Preserved diagnostic utility of dobutamine stress echocardiography in pacemaker-dependent patients with absolute chronotropic incompetence

Background The mechanism by which dobutamine induces ischemia is thought to depend on both increased chronotropy and inotropy. No data have been repor ted an the diagnostic power of dobutamine stress echocardiography (DSE) amo ng patients with fixed-rate pacemakers and absolute chronotropic incompeten ce. The purpose of this study was to determine the diagnostic and prognosti c utility of DSE in patients with fixed-rate, demand ventricular pacing who had no heart rate (HR) increase during DSE. Methods From 1990 to 1997, 22 patients remained pacemaker dependent with a fixed HR (69.7 +/- 5.7 beats/min) throughout DSE. Myocardial perfusion sing le-photon emission computed tomography and coronary angiographic studies we re reviewed when available. Clinical follow-up was determined for all patie nts at 15.4 +/- 7.7 months. Results In spite of absolute chronotropic incompetence during DSE, 11 (50%) of 22 patients hod test results consistent with inducible ischemia. Corona ry artery disease was confirmed in 6 (75%) of 8 who had coronary angiograms . Three of 11 patients with negative DSE underwent coronary angiography tha t confirmed the absence of significant coronary artery disease. DSE held a sensitivity of 100% and specificity of 60% in pacemaker-dependent patients with absolute chronotropic incompetence. At the time of clinical follow-vp, none of the patients with no inducible ischemia on DSE had an adverse isch emic cardiac event. Conclusions This study suggests that DSE has preserved diagnostic and progn ostic utility in pacemaker-dependent patients with absolute chronotropic in competence.