When is it safe to operate following myocardial infarction? (TrioBP).

History of recent myocardial infarction (MI) is known to be a significant risk factor for postoperative complications following elective, noncardiac surgery (NCS). Recommendation regarding the optimal time for elective surgery following MI has changed over time as additional data have become available. Herein, we examine the current evidence and recommendation regarding the most appropriate time interval for elective NCS following MI to minimize morbidity and mortality. In 1977, Goldman et al. published the first multifactorial index for the estimation of cardiac risk in patients undergoing NCS, an index still relied upon today for preoperative evaluation.1 From this 1,001-patient prospective study, Goldman et al. identified MI within 6 months as a preoperative risk factor for life-threatening or fatal cardiac complications, prompting a recommendation for delay of NCS by 6 months following MI. Over the decades that followed, multiple small and ultimately underpowered studies attempted to further clarify the risk associated with NCS following MI, leading to conflicting opinions about the optimal timing of NCS following MI. In an effort to account for advances made in perioperative care since the original Goldman recommendations, Larsen et al. published a 971,455-patient retrospective study in 2012 using the National Surgical Quality Improvement Program (NSQIP) database to identify risk factors for perioperative MI and to quantify present-day complication rates.2 From the study population, Larsen et al. identified 7,198 patients with recent MI, defined as MI within 6 months prior to NCS.2 These patients experienced perioperative MI at a rate of 2.0% as compared to 0.3% in their counterparts without recent MI. Odds ratios (OR) of perioperative MI following recent MI were calculated to be 4.6 to 6.5, with variation depending on subgroup analysis. Although Goldman et al. originally did not calculate an OR for risk of perioperative MI in patients with recent MI, Larsen et al. used Goldman's 1977 data to calculate an OR of 9.7 at that time.1, 2 A decrease in OR of perioperative MI from 9.7 to 4.6 to 6.5 represents a significant improvement in NCS outcomes of patients with recent MI. Despite the significant decrease in the rate of perioperative MI, Larsen et al. found that when perioperative MI does occur, the 30-day mortality remains high at 25.9%.2 This high associated mortality suggests caution in earlier scheduling of elective surgery following MI. Similarly, Livhits et al. used the California Patient Discharge Database (CPDD) to retrospectively analyze 563,842 patients undergoing post-MI hip surgery, cholecystectomy, colectomy, elective abdominal aortic aneurysm repair, and lower extremity amputation from 1999 to 2004.3 Unlike previous studies, however, Livhits et al. aimed to quantify the risk of postoperative complications in relation to the length of time from MI to surgery using 30-day intervals.3 In those patients without recent MI, 30-day postoperative MI rates and 30-day mortality were 1.4% and 3.9%, respectively. Variation between Larsen et al. and Livhits et al.'s complications rates is most likely attributable to differing severity of the surgeries studied. Rates of 30-day postoperative MI decreased significantly as the interval between recent preoperative MI and operation increased, from 32.8% (0–30 days) to 8.4% (61–90 days). Rates of 30-day mortality followed a similar trend from 14.2% (0–30 days) to 10.5% (61–90 days). Livhits et al.'s data suggest that these rates continue to decrease over time, although to a lesser degree, with MI and mortality rates of 5.9% and 9.9% (91–180 days), respectively.3 These risks remain significantly elevated for up to 1 year following MI.3 In a subsequent study, Livhits et al. similarly used the CPDD to analyze the impact of coronary artery revascularization on these same endpoints in patients with recent MI undergoing the same five operations (n = 16,478).4 Among patients with recent MI, revascularization by stenting (PCI) or coronary artery bypass grafting improved postoperative rates of reinfarction, 30-day mortality, and 1-year mortality each by at least 50%. Despite persistently elevated mortality associated with recent MI, when viewed together, Livhits et al.'s data demonstrate the most significant postoperative risk reduction occurs when time from MI to operation extends to ≥60 days, a risk that is further reduced in the setting of coronary artery revascularization (Table 1).1-4 In 2014, Fleisher et al. published the American College of Cardiology and American Heart Association (ACC/AHA) guidelines for perioperative cardiac evaluation prior to NCS.5 Using the literature available, the ACC/AHA advise that no fewer than 60 days should elapse between recent MI and NCS. Despite the significant risk reduction that occurs by 60 days post-MI, the associated risk remains elevated at 6 months, with a 30-day mortality of 9.9% at 91 to 180 days post-MI.3 Such data bolster the ACC/AHA recommendations for more extensive and individualized risk evaluation. Proper evaluation begins with the use of one of three multivariate risk indices: Revised Cardiac Risk Index, American College of Surgeons NSQIP Myocardial Infarction and Cardiac Arrest, or the American College of Surgeons NSQIP Surgical Risk Calculator. Functional status as assessed by the Duke Activity Status Index provides further information for preoperative risk assessment and should guide subsequent preoperative testing and treatment decisions. For patients with recent MI, preoperative 12-lead electrocardiogram is reasonable, whereas exercise stress testing can be reasonably forgone in these patients as long as functional status is excellent. In instances of poor or unknown functional status, preoperative stress testing may be reasonably considered. Notably, routine coronary angiography is not recommended for preoperative evaluation. The continuation of existing statin and β-blocker therapies has been demonstrated to be of benefit, but preoperative introduction of these medical therapies should be decided based on risk estimation and clinical judgment.5 As previously discussed, although PCI can mitigate the risk associated with preoperative MI,4 the ACC/AHA recommend against routine PCI outside of current clinical practice guidelines for PCI. Elective NCS should be delayed following PCI according to the following recommendations: 14 days following balloon angioplasty, 30 days following bare-metal stent placement, and 365 days following drug-eluting stent placement.5 Elective noncardiac surgery should be delayed by at least 60 days following MI, with complication risks further decreasing over time but persisting above baseline. Prior to such operations, the use of an approved cardiac risk calculator and functional status index should guide further management. Optimal preoperative evaluation requires the involvement of and communication between the entire patient care team, including the patient, surgeon, anesthesiologist, primary care physician, and any necessary consultants. The level of evidence for each of the articles cited is 1b (reference 1), 2b (references 2-4), and 2a (reference 5).