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Risk for Acute MI After Ophthalmologic Procedures
Quick Takes
- Among patients suffering a first-time AMI who underwent ophthalmologic surgery either 1 week or 4 weeks prior to the event, AMI occurred less frequently during the 7-day period immediately following surgery compared to a 7-day period 1 month following surgery.
- The relatively lower incidence of AMI during the immediate postoperative period compared to the equivalent length but more distant time period suggests lack of immediate causal relationship between ophthalmologic surgery and AMI.
Study Questions:
Does ophthalmologic surgery trigger risk of acute myocardial infarction (AMI)?
Methods:
Although large studies have shown that ophthalmologic surgery carries very low risk of adverse postoperative cardiovascular outcomes, findings from previous cohort studies have produced conflicting results. Using a methodologic approach designed to reduce cohort bias, the authors assess whether AMI may be triggered by ophthalmologic surgery.
Patients ≥40 years of age from the Norwegian Patient Registry (2008–2014) and Swedish National Patient Registry (2001–2014) who suffered first-time AMI were included in the study cohort if at any time during the 0- to 7-day interval prior to AMI (defined as the hazard period) or the 29- to 36-day interval prior to AMI (defined as the control period), that subject underwent ophthalmologic surgery. Using a case-crossover study design, the authors compared incidence of AMI during the hazard versus control periods, postulating that any increase in AMI risk relatable to surgery would manifest within the 7 postoperative days. Procedures were stratified by complexity and duration, and patients were categorized as low versus high risk based on presence or absence of documented medical comorbidities during the 2-year period preceding AMI.
Results:
Among the 806 patients meeting criteria for inclusion, AMI occurred during the hazard period in 344 subjects and during the control period in 462 subjects, indicating decreased risk of AMI during the hazard versus control period (odds ratio, 0.83; 95% confidence interval, 0.75- 0.91). No clear increase in relative risk was observed during the hazard period based on procedural duration, patient complexity, or use of general versus local anesthesia. However, the majority of cases were <20 minutes in length, were classified as low–intermediate complexitiy, and utilized general versus local anesthesia. The majority of patients were >65 years of age, and were considered low risk in terms of comorbidities.
Conclusions:
Short-term risk of AMI was lower in the 7-day time period immediately following ophthalmologic surgery compared to a 7-day period in the more distant future, between 29–36 days after ophthalmologic surgery. The impact of subpopulation effects cannot be excluded due to low representation of patients with high comorbidity burden and procedures lasting >20 minutes.
Perspective:
Although most previous trials have cited low risk of adverse cardiovascular outcomes after ophthalmologic surgery, and consensus guidelines recommend avoidance of preoperative cardiovascular testing prior to these cases, doubts seemed to remain based on findings from case-control studies, in which nonsurgical age-matched controls were utilized. The current study avoided cohort bias by using each subject as his/her own control. The authors speculate that the lower rate of AMI observed during the immediate postoperative period may be explained by the protective influence of optimization efforts, or by attrition bias if cases were cancelled or postponed due to preoperative findings suggesting a decompensated state of any kind. There was likewise insufficient detail to determine possible impact of management decisions such as interruption of antiplatelet medications or choice of anesthetic technique. Although these findings reinforce the rationale of avoiding preoperative cardiovascular testing in this population, the lower incidence of AMI in the immediate postoperative period may have resulted from avoidance of surgery during acute illness or decompensation, raising the likely protective effect of preoperative evaluation.
Clinical Topics: Acute Coronary Syndromes, Prevention
Keywords: Acute Coronary Syndrome, Anesthesia, General, Anesthesia, Local, Comorbidity, Diagnostic Tests, Routine, Myocardial Infarction, Ophthalmologic Surgical Procedures, Ophthalmology, Preoperative Period, Postoperative Period, Risk Factors, Secondary Prevention
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