Association of Chronotropic Competence With Intraoperative Hypotension and Vasopressor Requirement: A Retrospective Cohort Study.

BACKGROUND

Chronotropic incompetence (CI) is the inability to increase heart rate adequately during exercise to meet metabolic demands and is associated with adverse cardiovascular morbidity and mortality. CI is common in the perioperative population and can be diagnosed with preoperative cardiopulmonary exercise testing (CPET). The implications of CI for intraoperative hypotension and treatment with vasopressors are unclear.

METHODS

We conducted a single-center retrospective cohort study of patients who underwent CPET before surgery between January 2020 and August 2022. Chronotropic incompetence was defined as chronotropic index of <0.8. The outcomes were the time-weighted average of hypotension and total doses of vasopressors (phenylephrine-equivalent total doses, metaraminol, ephedrine and phenylephrine) in micrograms per kilogram per hour (µg·kg-1·h-1). Hypotension is defined as mean arterial pressure of <65 mm Hg. CPET parameters were compared between groups. T-tests and Mann-Whitney tests were used to compare continuous data, and Fisher's exact tests were used to compare categorical data. Multivariable linear regression analysis and sensitivity analysis were performed.

RESULTS

Of 195 patients included, 89 (46%) had CI. There was no difference between time-weighted average of hypotension for the group with no CI and the group with CI (median (IQR) 0.37 (0.21-0.74) vs 0.27 (0.07-0.76) mm Hg, P = .197). There was no difference in phenylephrine-equivalent total doses between the no CI and CI group (46 (11.6-97.3) vs 29.1 (13.2-61.6) µg·kg-1·h-1, P = .139). Those with no CI received higher doses of metaraminol (13.4 (5.82-20.8) vs 7.45 (2.99-14.8) µg·kg-1·h-1, BH-adjusted P = .034). There were no differences in doses of ephedrine (BH-adjusted P = .231) and phenylephrine (BH-adjusted P = .763). The CI group had lower resting heart rates (mean (SD) 88.2 (15.7) vs 80.2 (14.7) beats· min-1, P < .001), peak heart rates (155 (15.1) vs 125 (15.8) beats·min-1 P < .001), peak oxygen consumption (19.1 (5.9) vs 15.4 (3.8) mL·kg-1·min-1, P < .001) and oxygen consumption at the anaerobic threshold (10.6 (2.9) vs 9.4 (2.2) mL·kg-1·min-1 P = .002).

CONCLUSIONS

In this surgical cohort, chronotropic competence was neither associated with increased magnitude of hypotension nor with an increase in vasopressor requirements. These findings did not demonstrate an association between CI and intraoperative hypotension and highlight the complex interplay of factors governing perioperative hemodynamics.