Peri-operative cardiovascular morbidity: new developments

The stresses associated with surgery are extreme (many hours of organ trauma), ubiquitous (affecting nearly every biochemical pathway and organ system) and persistent (continual over days and manifesting over months). It is unsurprising, therefore, that 5% of the 30 million surgical population, or 1•5 million patients, suffer cardiac morbidity annually in the United States alone. The identification of these patients, which is pivotal to the solution of the problem of peri-operative cardiac morbidity, has eluded clinicians and researchers over the last four decades. Although various intraoperative and post-operative monitoring techniques, as well as specific cardiovascular therapies, have been suggested over the past decade, judicious expenditure of health care resources requires that we first identify those subpopulations likely to benefit from peri-operative high-risk management. Peri-operative myocardial infarction was identified as an important problem in the early 1950s; however, more than a decade passed before investigators attempted to identify subsets of high-risk patients. Two risk factors were consistently identified, recent myocardial infarction and congestive heart failure. Accordingly, the standard of care was changed. Multivariable analyses were introduced in the 1970s, and Goldman, Detsky and others, using routine history, physical and laboratory findings, identified independent predictors and constructed composite risk indices. The utility of such indices, however, remains controversial. In response to the limitations of routine testing, specialized pre-operative cardiac testing was initiated in the 1970s and increasingly used over the next two decades. More than 100 studies attempted to establish their utility for identification of high-risk subsets. Results differed markedly across studies, making interpretation and recommendation difficult. As our understanding evolved, we began to recognize that no one test can mimic all of the excitotoxic, inflammatory and haematological stress responses, inherently limiting pre-operative testing. The challenge, then, is to develop a pre-operative assessment approach tailored to the individual patient that will permit identification of specific risk.