Elevated preoperative heart rate is associated with cardiopulmonary and autonomic impairment in high-risk surgical patients

Background: Elevated preoperative heart rate (HR) is associated with perioperative myocardial injury and death. In apparently healthy individuals, high resting HR is associated with development of cardiac failure. Given that patients with overt cardiac failure have poor perioperative outcomes, we hypothesized that subclinical cardiac failure, identified by cardiopulmonary exercise testing, was associated with elevated preoperative HR > 87 beats min^-1 (HR > 87). Methods: This was a secondary analysis of an observational cohort study of surgical patients aged ≥45 yr. The exposure of interest was HR > 87, recorded at rest before preoperative cardiopulmonary exercise testing. The predefined outcome measures were the following established predictors of mortality in patients with overt cardiac failure in the general population: ventilatory equivalent for carbon dioxide (V E/V co₂) ratio ≥34, heart rate recovery ≤6 and peak oxygen uptake (V o₂) ≤14 ml kg^-1 min^-1. We used logistic regression analysis to test for association between HR > 87 and markers of cardiac failure. We also examined the relationship between HR > 87 and preoperative left ventricular stroke volume in a separate cohort of patients. Results: HR > 87 was present in 399/1250 (32%) patients, of whom 438/1250 (35%) had V E/V co₂ ratio ≥34, 200/1250 (16%) had heart rate recovery ≤6, and 396/1250 (32%) had peak V o₂ ≤14 ml kg^-1 min^-1. HR > 87 was independently associated with peak V o₂ ≤14 ml kg^-1 min^-1 {odds ratio (OR) 1.69 [1.12-3.55]; P=0.01} and heart rate recovery ≤6 (OR 2.02 [1.30-3.14]; P<0.01). However, HR > 87 was not associated with V E/V co₂ ratio ≥34 (OR 1.31 [0.92-1.87]; P=0.14). In a separate cohort, HR > 87 (33/181; 18.5%) was associated with impaired preoperative stroke volume (OR 3.21 [1.26-8.20]; P=0.01). Conclusions: Elevated preoperative heart rate is associated with impaired cardiopulmonary performance consistent with clinically unsuspected, subclinical cardiac failure. Clinical trial registration. ISRCTN88456378.