EVALUATION OF THE EFFECTIVENESS OF THE CANADIAN CARDIOVASCULAR SOCIETY GUIDELINES IN MINIMIZING CARDIAC EVENTS AFTER TOTAL KNEE ARTHROPLASTY

The study represents an analysis of the application of the Canadian Cardiovascular Society (CCS) guidelines for routine postoperative troponin testing after elective total knee arthroplasty (TKA) to reduce the mortality rate resulting from myocardial injury. The aim of the CCS recommendations is to decrease the mortality rate due to myocardial injury after noncardiac surgery. In general, according to the CCS, all orthopaedic patients who are more than 45 years of age must have daily troponin testing on postoperative days 0 through 3 during hospitalization. Troponin elevation of more than 30 ng/L is termed “myocardial injury after noncardiac surgery” (MINS). Elective TKA surgery is considered a low-intermediate cardiac risk surgery. Because of uncertainty regarding the validity of the CCS guidelines to detect the possible cardiac complications after elective surgery and the current push towards same-day discharge after lower extremity joint arthroplasty surgery we are conducting this study. Our objectives is to determine the prognostic relevance of applying CCS guidelines to patients undergoing elective TKA and to understand the impact of MINS on patient outcomes such as length of stay (LOS) in the hospital, morbidity, and mortality. A total of 715 patients were included in the study who underwent TKA surgery. The surgery was conducted by any of the seven orthopaedic consultants at University Hospital in London, Ontario during the year 2020. Inclusive criteria included all elective TKA patients over the age of 45 years, while emergency, revision, and bilateral TKA surgeries were excluded. The patients were categorized into four groups based on the CCS guidelines. Group A: patients who met the criteria to undergo screening protocol and had it applied; Group B: patients who met the criteria to undergo screening protocol and did not have it applied; Group C: patients who did not meet the criteria for screening protocol but had it applied; and Group D: patients who did not meet the criteria for screening protocol and did not have it applied. We measured different variables including age, gender, LOS in the hospital, ASA classification, type of anesthesia, and BMI. Several risk factors that might increase the risk to develop a cardiac event were evaluated such as history of cardiovascular disease, cerebrovascular disease, chronic renal disease, insulin dependent diabetes mellitus, RCRI score and smoking history. The outcomes of interest were any major cardiovascular event, cardiac consultation, and alteration in management. Others like additional cardiac investigation or treatment, and readmission or death within 30 days from surgery were also evaluated. The study cohort included 256 (35.8%) males and 459 (64.1%) females with an average age of 66 years. In patients, who undergo screening protocol, only 30 (4.1 %) patients had a troponin rise of >30 ng/L and developed MINS after their surgery and all of them are in group A. For patients who should have the screening protocol applied according to the CCS guidelines and are represented in group A and B, 11 (1.5%) patients out of them developed cardiac complication. Of the patients who were eligible to receive the protocol but did not receive it (Group B - 286 patients), only 2 patients had a 30-day readmission and without any mortality occurred due to cardiac events. On the other hand, only one patient (0.1%) from group C and D had to be readmitted within 30 days after the surgery and was due to pulseless electrical activity and resulted in death. 30 patients in group A and 3 patients in group C received subsequent subspecialty assessment, and only 16 (2.2%) patients from the entire cohort had a medication change as a result of the assessment. There was a mild increase in LOS in patients who received the MINS screening protocol in group A (255 patients) with a mean of 2.75 days compared to 2.24 day in patients who did not receive the aforementioned protocol who are represented in group B. The implementation of the CCS guidelines for routine postoperative troponin testing in elective TKA surgery did not significantly decrease the rate of cardiac events or mortality. The majority of the patients who developed MINS had no significant change in their management and did not develop any serious cardiac events later. Adherence to the CCS guidelines seemed to be associated with increased hospital stay and unnecessary medical expenses. Therefore, following the CCS guidelines without more specific criteria and additional clinical evidence may be unwarranted and should be re-evaluated to avoid unnecessary costs and resource utilization without providing significant clinical benefits.