July 14, 2004

Predictive Value Of Endothelial Dysfunction As Compared To Stress Testing For Perioperative Cardiovascular Events Following Vascular Surgery

Noyan Gokce, Joseph Raffetto, Maria Stoeckl, Joseph Palmisano, Ryan Beal, Ravin Davidoff, Joseph A. Vita, James O. Menzoian
Boston Medical Center, Boston, MA

Background: Our group previously demonstrated that endothelial dysfunction independently predicts future cardiovascular events in patients undergoing vascular surgery raising a potential clinical role for its use in preoperative risk assessment.

Objective: To compare the prognostic value of endothelial dysfunction to established methods of risk stratification such as stress echocardiography and nuclear imaging for short-term perioperative cardiovascular complications.

Methods: Seventy-one patients (age 66±10 yr, 69% male) scheduled for peripheral vascular surgery underwent preoperative stress testing and concomitant ultrasound examination of brachial artery flow-mediated vasodilation as assessment of endothelial function. Endothelial dysfunction was defined as flow-mediated dilation <8% based on our previous studies, and a positive stress test defined as inducible cardiac ischemia in any coronary territory. Patients with intercurrent coronary revascularization prior to their peripheral vascular operation were excluded. Subjects were followed prospectively for 30 days after surgery.

Results: Seventeen patients had a postoperative event, including death (2), myocardial infarction (6), unstable angina (2), stroke (1), and elevated troponin reflecting myocardial injury (6). Preoperative stress tests were negative in 11 of 17 patients that subsequently suffered a cardiovascular event, whereas endothelial function was normal in only 1 of 17 subjects with an adverse outcome. Flow-mediated dilation had a high sensitivity of 94%, specificity of 32%, positive predictive value of 31%, and negative predictive value of 95% (OR: 7.6, P=0.03). In contrast, stress testing provided a low sensitivity of 35%, a specificity of 74%, positive predictive value of 30%, and negative predictive value of 78% (OR: 1.5, P=0.54).

Conclusions: In this select group of vascular surgery patients, endothelial function assessment yielded incremental prognostic information and demonstrated a high negative predictive value for adverse events. The findings provide evidence for a pathophysiological link between impaired endothelial homeostasis and cardiovascular risk. These results also suggest that combining different preoperative tests may increase diagnostic accuracy.