Stress testing in patients with implantable cardioverter-defibrillators: a preliminary report

This retrospective study was undertaken to assess the responses to, and complications associated with, stress testing in patients with implantable cardioverter-defibrillators (ICDs). Primary end points were occurrence of malignant ventricular arrhythmias, onset of burst pacing or ICD firing, cardiopulmonary resuscitation, or death during or soon after stress testing. Secondary end points were urgent coronary revascularization and/or hospital readmission for cardiovascular complications. During a 4-year period, 1734 patients underwent ICD implantation or generator replacement at our institution; 84 patients (mean age +/- SD, 67+/-12 years; 76% men) subsequently underwent 107 stress tests, including 44 exercise and 63 pharmacologic (22 dobutamine, 41 dipyridamole) evaluations. None of the ICDs were inactivated before testing. All tests were supervised by specially trained paramedical personnel, with a physician immediately available. Four patients had self-terminating, nonsustained ventricular tachycardia at peak stress. None had sustained ventricular tachycardia requiring emergent therapy. There were no deaths or hospital readmissions for ventricular arrhythmias. These findings suggest that stress testing is feasible in patients with ICDs and that it can be performed without pretest inactivation.