Abstract 316: Arm Exercise Heart Rate, Stress Test Findings and Outcome

Abstract

Attainment of 85% age-predicted peak heart rate (APPHR) during leg exercise is widely accepted and emphasized in clinical textbooks as a condition for adequate diagnostic stress test sensitivity. However, there is little direct evidence for this belief and relationships among peak heart rate, diagnostic sensitivity, coronary revascularization and mortality are poorly characterized. In addition, the prognostic significance of chronotropic incompetence as a predictor of mortality is underappreciated and there is almost no data relating arm exercise heart rate responses to abnormal stress test results and mortality. Thus, the purpose of this study was to investigate relationships among arm exercise heart rate responses, abnormal stress tests findings, coronary revascularization and mortality in patients who could not perform leg exercise. From 1997 to 2002, we conducted arm cycle ergometer stress tests on 446 veterans aged 64±11 years, of whom 253 underwent myocardial perfusion imaging (MPI). We evaluated associations of quartiles of %APPHR and heart rate reserve (%HRR) with an abnormal electrocardiographic (ECG ST depression ≥ 1 mm) or MPI stress test, coronary revascularization and all-cause mortality during follow-up ≥ 10 yrs. An abnormal arm exercise ECG occurred in 62/427 (14.5%) of patients with an interpretable ECG. MPI was abnormal in 157/253 (62.1%). Over 12.0±1.3 yrs. follow-up, there were 256 deaths (57.4%) and 105 patients (23.5%) underwent coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI). An abnormal arm exercise ECG was directly associated with quartile of %APPHR (p = 0.009) and %HRR (p = 0.02) but an abnormal arm exercise MPI exhibited an inverse trend (p = 0.10 and 0.12, respectively). There was a sharp upward inflexion point for increased percent of abnormal arm exercise ECG tests at 69%APPHR. Results for abnormal ECG and MPI tests were similar for patients taking beta blockers. Both %APPHR and %HRR were inversely related to all-cause mortality (p = 0.02 and p = 0.004, respectively) after adjustment for significant demographic and clinical variables. CABG and PCI were each predicted by an abnormal arm exercise ECG (p < 0.04) and PCI alone by abnormal MPI (p= 0.02) with no interaction of %APPHR or %HRR. We conclude that higher %APPHR and %HRR are associated with greater likelihood of an abnormal arm exercise ECG, particularly above 69%APPHR, but borderline reduced likelihood of abnormal arm exercise MPI in patients unable to perform leg exercise. An abnormal arm exercise ECG predicts CABG and PCI and MPI predicts PCI with no apparent influence of %APPHR or %HRR. Higher arm exercise %APPHR and %HRR are related to lower all-cause mortality.