Age, Hypertension, and Exercise Capacity are Independently Associated with Likelihood of Multi-Vessel Disease in Patients Referred for Treadmill Exercise Testing: The Intermediate-High-Workload Treadmill Score (IHWTS).

Abstract

To identify factors that increase the specificity of the treadmill exercise test (TMET), and develop a novel scoring system which accounts for functional capacity to aid in determining the need for further testing. We retrospectively evaluated the electronic health records of 600 patients who had positive TMET results and follow-up stress echocardiography from 1-January-2004, through 31-December-2016. Correlations between clinical and aerobic variables and multivessel disease (MVD) were determined. Duke Treadmill Score (DTS) was calculated and compared with a novel scoring system titled the Intermediate-High-Workload Treadmill Score (IHWTS) that used variables associated with MVD. In total, 124 of 600 patients (21%) had coronary catheterization, and 51 of these patients (41%) had MVD. Mean (SD) DTS was -2.10 (6.3) among patients with MVD vs -0.16 (5) among patients without MVD (p = 0.06). Mean (SD) functional aerobic capacity (FAC) was 76% (20%) among patients with MVD vs 90% (21%) among patients without MVD (p 0.001). Mean (SD) metabolic equivalent (MET) was 7 (2) among patients with MVD vs 8 (2) among patients without MVD (p = 0.002). Only 6 (12%) of patients with MVD achieved 9 MET or greater on TMET. DTS less than 4 did not distinguish between patients with and without MVD (p = 0.67). Age, hypertension and FAC were independently associated with MVD (all p 0.05). Our novel scoring system IHWTS utilized age, hypertension, and FAC appeared comparable to DTS to risk-stratify patients regardless of baseline symptoms. Clinical parameters such as hypertension along with exercise functional capacity should be considered when evaluating a positive TMET result in patients that achieve an intermediate-high workload 5 Metabolic Equivalents (METs).