Baseline natriuretic peptide levels in relation to myocardial ischemia, troponin T release and heart rate variability in patients undergoing major vascular surgery.

Background: This study was conducted to determine the association between baseline N-terminal pro-B-type natriuretic peptide (NT-proBNP) and myocardial ischemia, troponin T release and heart rate variability (HRV) in patients undergoing major vascular surgery.

Methods: In a prospective study, 182 vascular surgery patients were evaluated by clinical risk factors, dobutamine stress echocardiography and baseline NT-proBNP levels. Myocardial ischemia was detected by continuous 12-lead electrocardiographic monitoring starting 1 day before to 2 days after surgery. Troponin T (>0.03 ng/ml) was measured on day 1, 3 and 7 postoperatively and before discharge. HRV was measured at the day prior to surgery.

Results: The median NT-proBNP level was 184 ng/l (interquartile range: 79-483 ng/l). Myocardial ischemia was detected in 21% and troponin T release in 17% of patients. After adjustment for clinical risk factors and stress echocardiography results, higher NT-proBNP levels (per 1 ng/l increase in the natural logarithm of NT-proBNP) were associated with a higher incidence of myocardial ischemia (odds ratio: 1.59, 95% confidence interval: 1.21-2.08, P<0.001) and troponin T release (odds ratio: 1.76, 95% confidence interval: 1.33-2.34, P<0.001). The optimal cutoff value of NT-proBNP to predict ischemia and/or troponin T release was 270 ng/l (area under the curve: 0.70). Higher baseline NT-proBNP levels were also associated with a larger ischemic burden at electrocardiographic monitoring (r=0.22, P=0.03). No significant correlation, however, was found between NT-proBNP and preoperative HRV (r=-0.024, P=0.78).

Conclusion: Elevated baseline NT-proBNP levels are significantly associated with perioperative myocardial ischemia and troponin T release, but not with preoperative HRV in patients undergoing major vascular surgery.