Cardiovascular risk factors for perioperative myocardial injury
MetadataShow full item record
Background: Myocardial injury affects up to one in three patients undergoing non-cardiac surgery. However, very little is known about the underlying pathophysiology. In the general population, patients with elevated resting heart rate are at increased risk of cardiac events, mortality, heart failure and autonomic dysfunction, while hypertension is a well described risk factor for cardiovascular disease. I hypothesised that common abnormalities of heart rate or blood pressure were associated with myocardial injury after non-cardiac surgery. Methods: This thesis comprises a series of secondary analyses of data from five prospective multi-centre epidemiological studies of surgical patients. The main outcome of interest was myocardial injury, defined using objective measurement of cardiac troponin. I used logistic regression analysis to test for association between exposures and outcomes. Results: In a large international cohort, patients with high preoperative heart rate had increased risk of myocardial injury and patients with very low preoperative heart rate had reduced risk of myocardial injury. Patients with elevated preoperative pulse pressure had increased risk of myocardial injury, independent of existing hypertension or systolic blood pressure. High heart rate, or high or low systolic blood pressure during surgery, was associated with increased risk of myocardial injury. In a separate study, elevated preoperative heart rate was associated with cardiopulmonary and autonomic dysfunction, and reduced left ventricular stroke volume, suggestive of heart failure. Finally, autonomic dysfunction, identified using cardiopulmonary exercise testing, was associated with elevated preoperative heart rate, elevated plasma NT-Pro-BNP (indicative of heart failure) and postoperative myocardial injury. Conclusions: Elevated preoperative heart rate, autonomic dysfunction and subclinical heart failure may be part of a common phenotype associated with perioperative myocardial injury. Further research is needed to characterise the pathological processes responsible for myocardial injury, and to identify potential therapeutic targets.
- Theses