[Analysis of 10-year survival of patients after coronary artery bypass surgery with type 5 myocardial infarction associated with coronary bypass dysfunction].

Background: Currently, effective methods have been developed to protect the myocardium during operations with cardiopulmonary bypass with different pharmacological effects on cardiomyocytes, the method of administration and the temperature regime. At the same time, the problem of myocardial damage and myocardial infarction associated with the surgical procedure remains a frequent and urgent problem that significantly affects the result of surgical treatment. A set of factors, their qualitative and quantitative characteristics, determined by several scientific groups and used in clinical practice for the diagnosis of perioperative myocardial infarction, differ significantly. Such a variety of definitions affects the analysis of both immediate and long-term results in patients with intraoperative myocardial injury.

Objective: The purpose of the study was to analyze the ten-year survival of patients after elective coronary artery bypass grafting, diagnosed in the early postoperative period with type 5 myocardial infarction and dysfunction of coronary bypass grafts.

Patients and methods: From 2011 to 2020, a total of 8801 patients underwent isolated coronary artery bypass grafting at the Federal Center of Cardiovascular Surgery. Of these, 196 (2.23%) patients were subjected to emergency coronary graft angiography due to signs of myocardial ischemia and manifestations of acute heart failure.

Eligibility criteria: patients with stable coronary artery disease who were diagnosed as having type 5 myocardial infarction after elective coronary artery bypass grafting according to the Fourth Universal Definition of Myocardial Infarction, based on Troponin I >10 times the 99th percentile and acute coronary bypass graft dysfunction revealed during emergency coronary angiography (n=111/1.26%).

Exclusion criteria: patients who died in the clinic within 30 days (n=10/0.11%), lost-to-follow-up patients (n=20/0.23%). The primary endpoint was long-term mortality, with secondary endpoints being adverse cardiovascular events. Using a random number generator for comparative analysis, group II was formed, consisting of 196 patients with an uncomplicated postoperative period. The exclusion criteria were as follows: in-hospital mortality (n=1/0.01%), acute type 5 infarction (n=5/0.06%), and loss to follow-up (n=27/0.31%). After applying the exclusion/inclusion criteria, there were 81 patients in group I and 163 patients in group II. Contact with patients was carried out using a telephone survey.

Results: Analyzing long-term overall mortality and the incidence of adverse cardiovascular events using the Kaplan-Meier method, no statistically significant differences were found in groups I and group II: 102.6±4.8 months versus 111.3±3 months (log-rank test, p=0.115) and 90.9±4.2 months versus 107.4±3.3 months (log-rank test, p=0.087), respectively. Comparing cardiovascular mortality, statistically significant events were found: in group I amounting to 111.4±4 months and in group II to 121.2±1.9 months (log-rank test, p=0.029). Evaluating the survival of patients undergoing CABG with dysfunction of coronary bypass grafts, depending on the time of coronary bypass surgery (more than 24 hours after surgery and less than 24 hours after surgery) and subsequent treatment, showed no statistical differences in long-term survival (log-rank test, p=0.354), when analyzing cardiovascular mortality, there were statistically significant differences (log-rank test, p=0.029), and adverse cardiovascular events tended to occur earlier in the group of patients who underwent emergency bypass angiography within >24 hours after surgery. The multivariate Cox regression analysis revealed in group I an increase of the risk for developing a fatal outcome from all causes in the presence of a history of stroke by 16.7 times (p=0.001), pulmonary hypertension by 3.345 times (p=0.034), the risk of cardiovascular vascular lethality was found to increase 18.5-fold with a history of stroke (p=0.021), with the factor of pulmonary hypertension increasing the risk 6.6-fold (p=0.008).

Conclusion: Comparing the 10-year cardiovascular mortality in group I (patients with type 5 MI and shunt dysfunction) with the control group revealed statistically significant differences. The factors increasing the risk of long-tern cardiovascular mortality in group I were pulmonary hypertension and a history of acute cerebral ischemia.