Abstract
Prior to TJR, clinical cardiovascular risk assessment is typically limited by severe exercise restrictions. Noninvasive pharmacological cardiovascular stress tests may predict major perioperative cardiovascular events in patients undergoing orthopaedic surgery. We undertook a pilot study to inform the feasibility of a large prospective cohort study.
Patients were eligible if they were aged > forty-five, undergoing elective TJR, and had known atherosclerotic disease or risk factors for atherosclerotic disease. We recruited patients at the Hamilton Health Sciences, Henderson Hospital. Prior to surgery patients underwent dipyridamole stress perfusion imaging and dobutamine stress echocardiography. For both tests the interpreters evaluated seventeen myocardial segments and were blinded to information about patients’ clinical risk factors. The attending surgeons and research personnel following patients after surgery were blinded to results of the noninvasive pharmacological cardiovascular stress tests. All patients had an ECG performed and troponin T drawn six to twelve hours postoperatively and on the first, second and third days after surgery.
Starting in November 2005 we recruited thirty patients over six months; seventeen (57%) patients were male, twenty-one (70%) underwent TKA, and nine (30%) underwent THA. The length of surgery was seventy-two (SD 38) minutes and the length of hospital stay was five (SD 3) days. We successfully followed all patients to thirty days after surgery. Three patients (10%; 95% CI, 3–26%) suffered a perioperative myocardial infarction. Twenty nine patients underwent dipyridamole stress perfusion imaging prior to surgery; a reversible defect involving 30–50% of the myocardium increased the likelihood of a perioperative myocardial infarction (likelihood ratio [LR] 4.0; 95% CI, 1.2–13.3). Twenty-six patients underwent dobutamine stress echo-cardiography; a reversible defect increased the likelihood of a perioperative myocardial infarction (LR 4.0; 95% CI, 0.7–22.9).
This pilot study demonstrates the need for, and feasibility of, a large prospective cohort study to determine if preoperative noninvasive pharmacological cardiovascular stress testing has additional predictive value, beyond clinical variables, for the occurrence of myocardial infarction in patients undergoing major hip and knee surgery.
Correspondence should be addressed to: Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
