Major adverse events associated with inducible cardiac ischemia during treadmill exercise testing for peripheral artery disease

Background: The coexistence of coronary artery disease and peripheral artery disease (PAD) is well-established. Whether myocardial ischemia by electrocardiography during treadmill testing to evaluate PAD severity is associated with adverse cardiac and limb events has not been established. The aim of the current study is to assess the risk of major adverse cardiac events (MACE), major adverse limb events (MALE), and all-cause mortality in patients with evidence of myocardial ischemia on ECG compared with those without ischemia in patients undergoing treadmill testing for PAD evaluation. Methods: Patients undergoing treadmill exercise ankle-brachial index (ABI) evaluation (January 1, 2003, to December 31, 2006) were identified using the Mayo Clinic Gonda Vascular Laboratory database. Patients with ischemia by electrocardiogram (ECG) were age and sex matched to patients without ischemia. Outcomes were compared by ECG category. Results: Of 4128 patients who underwent treadmill exercise, 170 (4.1%) had inducible myocardial ischemia by ECG. These were matched with 340 patients without ischemia. The positive ECG group had a higher percentage of diabetes mellitus (31.2% vs 21.8%; P =.02), carotid artery disease (22.4% vs 13.2%; P =.009), exercise-induced angina (14.1% vs 2.9%; P <.0001), and dyspnea (60.6% vs 35.6%; P <.0001). While the resting ABI was similar, the postexercise ABI was lower in the positive ECG group (0.5 vs 0.7; P =.04). After a median follow-up of 8 years, MACE were significantly greater in the positive ECG group (62.4% vs 46.5%; P <.001). MALE were significantly less frequent (17.1% vs 23.2%; P =.02), without an increased risk of amputation. In multivariable analysis, inducible ischemia was associated with higher incidence of MACE (hazard ratio, 1.65; 95% confidence interval, 1.25-2.16; P <.001) and lower incidence of MALE (hazard ratio, 0.51; 95% confidence interval, 0.31-0.84; P <.05). Conclusions: ECG monitoring during vascular treadmill testing identified a subset of patients with more frequent MACE but less MALE.