Prognostic Markers of Outcome in Patients Undergoing Infra-inguinal Revascularisation: A Prospective Observational Pilot Study

Abstract

Objectives: The aim was to investigate whether cardiopulmonary exercise testing (CPET) variables derived from cycle and arm ergonometry correlate, and whether CPET variables and pre-operative N-terminal pro-brain natriuretic peptide (NT-proBNP) have prognostic significance and if the combination of the two has incremental value.

Methods: A prospective observational pilot study was conducted; 70 patients who underwent infra-inguinal bypass surgery were recruited. Pre-operatively subjects underwent CPET with both arm and leg ergonometry, to measure peak oxygen consumption, anaerobic threshold (AT), and ventilatory equivalents. In addition pre-operative serum samples of NT-proBNP were obtained. The primary endpoint was 1 year all-cause mortality; in addition, data were collected on complications, morbidity, length of stay, and major adverse cardiac events (MACE).

Results: The 1 year mortality rate was 6%, the overall complications rate was 23%, and the combined incidence of MACE and 1 year mortality was 10%. Cycle ergonometry peak VO₂ 14 mL/kg/min (RR 5.5, 95% CI 1.4-22.4, p = .007) and AT < 10mL/kg/min (RR 3.0, 95% CI 1.1-7.0, p = .03) were predictors of post-operative complications. Pre-operative NT-proBNP > 320 ng/L (RR 18, 95% CI 2.5-140 p = .0003) was the sole predictor of 1 year mortality or MACE.

Conclusion: The measurement of pre-operative NT-proBNP in peripheral vascular disease patients undergoing infra-inguinal bypass can predict 1 year mortality and MACE. CPET variables from cycle ergonometry are predictors of post-operative complications in this patient group.

Keywords: Anaerobic threshold; Arm crank; Bike test; Cardiopulmonary Exercise test; Lower limb revascularisation; NT-proBNP; Peak VO(2); Peripheral vascular disease.