Exercise Testing in the Presence of Complete Heart Block

A 28-yr-old female presented for preoperative evaluation. The resting ECG revealed sinus arrhythmia with complete heart block with a junctional escape rhythm and a ventricular rate of 43 bpm. The patient was in no apparent distress, and resting blood pressure was 80/50 mm Hg. Physical examination was largely unremarkable, with the exception of a soft, nontender, movable abdominal mass. The patient complained of mild dyspnea with stair climbing, but she was otherwise asymptomatic. Although high-grade atrioventricular (AV) block is considered a relative contraindication for exercise testing, this patient was referred for an exercise ECG stress test to assist in determining whether a electronic pacemaker or other therapy was necessary. A symptom-limited maximal ECG treadmill test was performed using the Bruce protocol. The resting HR before the test was 47 bpm, and resting blood pressure was 70/50 mm Hg. Beginning with the first stage of the test, sinus rhythm with a first-degree AV block was observed. The patient achieved 10.2 METs, with an HRpeak of 122 bpm and a peak blood pressure of 122/70 mm Hg. No ectopy was noted during exercise, no ST segment changes occurred during exercise or recovery, and the patient remained asymptomatic. The test was terminated because of the patient's inability to keep pace with the treadmill. On the basis of these results, no medical therapy or electronic pacemaker was recommended at this time, and the patient was permitted to undergo surgery for uterine fibroid tumors. This case illustrates that although complete heart block is a relative contraindication to exercise testing in some patients, the benefits of testing outweigh the risks.