title: Exercise capacity and heart rate responses to exercise as predictors of short-term outcome among patients with stable coronary artery disease.
abstract: Although exercise capacity (EC) and autonomic responses to exercise predict clinical outcomes in various populations, they are not routinely applied in patients with coronary artery disease (CAD). We hypothesized that the composite index of EC and exercise heart rate responses would be a powerful determinant of short-term risk in CAD. Patients with angiographically documented stable CAD and treated with β blockers (n = 1,531) underwent exercise testing to allow the calculation of age- and gender-adjusted EC, maximal chronotropic response index (CRI), and 2-minute postexercise heart rate recovery (HRR, percentage of maximal heart rate). Cardiovascular deaths and hospitalization due to heart failure, registered during a 2-year follow-up (n = 39, 2.5%), were defined as the composite primary end point. An exercise test risk score was calculated as the sum of hazard ratios related to abnormal (lowest tertile) EC, CRI, and HRR. Abnormal EC, CRI, and HRR predicted the primary end point, involving 4.5-, 2.2-, and 6.2-fold risk, respectively, independently of each other. The patients with intermediate and high exercise test risk score had 11.1-fold (95% confidence interval 2.4 to 51.1, p = 0.002) and 25.4-fold (95% confidence interval 5.5 to 116.8, p <0.001) adjusted risk for the primary end point in comparison with the low-risk group, respectively. The addition of this risk score to the established risk model enhanced discrimination by integrated discrimination index and reclassification by categorical and continuous net reclassification index (p <0.001 for all). In conclusion, the composite index of EC and heart rate responses to exercise and recovery is a powerful predictor of short-term outcome in patients with stable CAD.
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland. Electronic address: antti.m.kiviniemi@oulu.fi.
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Samuli
authors.initials: S
authors.lastname: Lepojärvi
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Tuomas V
authors.initials: TV
authors.lastname: Kenttä
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: M Juhani
authors.initials: MJ
authors.lastname: Junttila
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Juha S
authors.initials: JS
authors.lastname: Perkiömäki
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Olli-Pekka
authors.initials: OP
authors.lastname: Piira
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Olavi
authors.initials: O
authors.lastname: Ukkola
authors.affiliation: Biomedical Engineering Research Group, Department of Computer Science and Engineering, University of Oulu, Oulu, Finland.
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland; Department of Applied Sciences, London South Bank University, London, United Kingdom.
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000503:physiopathology*; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors; D013997:Time Factors