Surgical revascularization after acute myocardial infarction

Appropriate Timing of Coronary Artery Bypass Graft Surgery for Acute Myocardial Infarction Patients: A Meta-Analysis

Background

Currently, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are commonly used in the treatment of coronary atherosclerotic heart disease. But the optimal timing for CABG after acute myocardial infarction (AMI) is still controversial. The purpose of this article was to evaluate the optimal timing for CABG in AMI.

Methods

We searched the PubMed, Embase, and Cochrane library databases for documents that met the requirements. The primary outcome was in-hospital mortality. The secondary outcomes were perioperative myocardial infarction (MI) incidence and cerebrovascular accident incidence.

Results

The search strategy produced 1,742 studies, of which 19 studies (including data from 113,984 participants) were included in our analysis. In total, 14 studies compared CABG within 24 h with CABG late 24 h after AMI and five studies compared CABG within 48 h with CABG late 48 h after AMI. The OR of in-hospital mortality between early 24 h CABG and late 24 h CABG group was 2.65 (95%CI: 1.96 to 3.58; P < 0.00001). In the undefined ST segment elevation myocardial infarction (STEMI)/non-ST segment elevation myocardial infarction (NSTEMI) subgroup, the mortality in the early 24 h CABG group (OR: 3.88; 95%CI: 2.69 to 5.60; P < 0.00001) was significantly higher than the late 24 h CABG group. Similarly, in the STEMI subgroup, the mortality in the early 24 h CABG group (OR: 2.62; 95% CI: 1.58 to 4.35; P = 0.0002) was significantly higher than that in the late 24 h CABG group. However, the mortality of the early 24 h CABG group (OR: 1.24; 95%CI: 0.83 to 1.85; P = 0.29) was not significantly different from that of the late 24 h CABG group in the NSTEMI group. The OR of in-hospital mortality between early 48 h CABG and late 48 h CABG group was 1.91 (95%CI: 1.11 to 3.29; P = 0.02). In the undefined STEMI/NSTEMI subgroup, the mortality in the early 48 h CABG group (OR: 2.84; 95%CI: 1.31 to 6.14; P < 0.00001) was higher than the late 48 h CABG group. The OR of perioperative MI and cerebrovascular accident between early CABG and late CABG group were 1.38 (95%CI: 0.41 to 4.72; P = 0.60) and 1.31 (95%CI: 0.72 to 2.39; P = 0.38), respectively.

Conclusion

The risk of early CABG could be higher in STEMI patients, and CABG should be delayed until 24 h later as far as possible. However, the timing of CABG does not affect mortality in NSTEMI patients. There was no statistical difference in perioperative MI and cerebrovascular accidents between early and late CABG.

Timing of Coronary Artery Bypass Grafting in Acute Coronary Syndrome: A National Analysis

BACKGROUND

Timing of surgical revascularization for acute coronary syndrome (ACS) remains debated. We assessed the impact of timing to CABG on mortality and resource utilization in a national cohort.

METHODS

Adults admitted for ACS in the 2009-2018 National Inpatient Sample were grouped by time from coronary angiography to CABG (Δt): 0, 1-3, 4-7, and >7 days. Generalized linear models were fit to evaluate associations between Δt and in-hospital mortality and hospitalization costs. Timing and mortality of CABG for ACS was compared between high-performing hospitals (below the median risk adjusted mortality for all CABG and valve operations) and others.

RESULTS

Of 444,065 patients, time to CABG was Δt=0 in 12.3%, Δt=1-3 in 57.3%, Δt=4-7 in 26.3%, and Δt>7 in 4.2%. Risk-adjusted mortality was greatest at Δt=0 (4.5%, 95% confidence interval, CI, 4.1-4.9) and Δt>7 (4.0%, 95% CI 3.4-4.7), but similar for operations performed at Δt=1-3 (1.8%, 95% CI 1.7-1.9) and Δt=4-7 (2.1%, 95% CI 1.9-2.3). Compared to Δt=1-3, hospitalization costs were greater by $6,400 (95% CI 5,900-6,900) for Δt=4-7 and $21,200 (95% CI 19,800-22,600) for Δt>7. High-performing hospitals had similar time to CABG as others (2 vs 2 days, p=0.17), but lower mortality (0.9% vs 3.3%, p<0.001).

CONCLUSIONS

Revascularization on day 1-3 and 4-7 led to comparable in-hospital mortality, with greater rates on day 0 and after day 7. Costs were greater for revascularization at day 4-7 compared to day 1-3. These findings support the reduction of time to revascularization to 1-3 days when deemed clinically appropriate and feasible.

Optimal timing of coronary artery bypass grafting in acute myocardial infarction

The timing of surgical coronary artery revascularization after an acute myocardial infarction is not well defined. The inherent difficulties of mobilizing a surgical team at odd hours has led to the adoption of a percutaneous coronary intervention strategy when possible or a clot-busting drug regimen when percutaneous coronary intervention is not available. Despite the difficulties and risks of surgical revascularization, there are situations where it may be indicated. We conducted a review of the literature to better understand the timing, scope, and risks of surgical coronary revascularization after an acute myocardial infarction.

Timing of revascularization after acute myocardial infarction

The optimal timing of surgical revascularization after acute myocardial infarction remains controversial. Higher mortality after emergency coronary artery bypass has been documented. We retrospectively reviewed 278 patients who underwent coronary artery bypass between 2005 and 2007. The time from onset of myocardial infarction to surgical revascularization was the basis for dividing patients into 3 groups: surgery was performed within 24 h in group 1, at 24-72 h in group 2, and after 14 days in group 3. There was a definite relationship between the timing of revascularization and the outcome of surgery. Group 1 had a mortality rate of 11.7%, group 2 had 7% mortality, and group 3 had 2.5% mortality. Group 1 had the highest incidence of postoperative complications. Surgical revascularization within 24 h of acute myocardial infarction was associated with significantly higher risks of mortality and morbidity than procedures performed after 72 h.

Timing of nonemergent coronary artery bypass grafting and mortality after non-ST elevation acute coronary syndrome

BACKGROUND

The purpose of this study was to determine the association between time to coronary artery bypass grafting (CABG) and mortality among patients admitted with non-ST elevation acute coronary syndrome (NSTEACS). Patients are increasingly being referred for CABG soon after NSTEACS, although few data exist to guide the optimal timing of bypass surgery.

METHODS

We identified a cohort of all patients who underwent nonemergent CABG within 60 days of hospitalization for NSTEACS in the province of Alberta, Canada, from 2000 to 2004. Time from admission to CABG was categorized as early (2-7 days), intermediate (8-14 days), or late (15-60 days-reference group). The primary outcome was mortality occurring within 30 days of surgery.

RESULTS

Of the total cohort of 1,454 patients, 213 (14.6%) underwent early, 637 (43.8%) underwent intermediate, and 707 (48.6%) underwent late CABG surgery. In the final adjusted model time to CABG was not statistically significant as an independent predictor of short-term mortality. Compared to late CABG, there was a nonsignificant increased risk of mortality for those undergoing early (hazard ratio 2.36, 95% CI 0.72-7.76) and intermediate (hazard ratio 1.68, 95% CI 0.76-3.72) CABG surgery.

CONCLUSIONS

Time from admission to CABG was not associated with an increased risk of short-term mortality. However, there was a trend toward increased mortality with early CABG, and this study does not exclude the presence of a modest risk association between timing of CABG and short-term mortality.

Timing of bypass surgery in stable patients after acute myocardial infarction

OBJECTIVES

To determine the optimal timing for bypass surgery in stable patients after acute myocardial infarction (MI).

BACKGROUND

Coronary artery bypass graft surgery (CABG) is a proven treatment for coronary artery disease. Because of the hypothesized risk of hemorrhagic transformation, it had become common practice to wait four to six weeks after MI. Recently, improvements in surgical and perioperative management, as well as an increase in pre-CABG in-hospital waiting times and excess burden on health care resources, have pushed surgeons to operate earlier. The optimal timing for a stable patient to undergo CABG after MI is unclear, because there have been no randomized trials to answer this question.

METHODS

The published literature comparing early versus late surgical revascularization procedures in stable post-MI patients was reviewed.

RESULTS

No randomized, prospective trials were found; however, several retrospective studies were identified. Most series examining Q wave MIs showed that mortality is higher in the early stages post-MI and progressively decreases with time post-MI. When studies examined non-Q wave MIs separately, there appeared to be less of a mortality difference between early and late surgical revascularization. There was a large disparity between the definitions of early surgery post-MI among the studies, some as early as 6 h and others up to eight days. Factors that increased mortality include abnormal left ventricular function and urgency of surgery, and some studies found risk models helpful to define increased risk after infarction. The possible increased risk of early surgery may be balanced against the potential for improved remodelling, improved quality of life and decreased hospital stay costs.

CONCLUSIONS

There is a need for a randomized, prospective trial examining the optimal timing for CABG in stable post-MI patients.

Timing of coronary artery bypass graft surgery following acute myocardial infarction: a critical literature review

Despite more than 30 years' experience with coronary artery bypass surgery, controversy still exists about the optimal timing of surgical revascularization following acute myocardial infarction. To review the published information on this topic, a Medline search of the literature published between 1984 and October 2000 was performed. After reviews and individual case reports we re excluded, 11 retrospective and prospective studies remained for analysis. Pervasive heterogeneity with respect to inclusion criteria, outcome measurement, definitions, variance among studies of measured time between myocardial infarction (MI) and coronary artery bypass graft (CABG), differences in study endpoints, and evolution of surgical techniques and medical regimens over this time precluded formal meta-analysis. Although prospective randomized trials are lacking, the preponderance of data from the 11 retrospective and prospective observational studies suggests that timing of bypass surgery after infarction is not an independent predictor of outcome and that delaying coronary bypass surgery for an arbitrary period of time following acute MI is unwarranted. Rather, ventricular function, post-infarction ischemia, noncardiac comorbid conditions, and the urgency of the surgery itself constitute the important predictors of perioperative mortality, and these clinical factors should be used to estimate perioperative risk and decide upon the risk:benefit relationship for CABG in this patient population.

Appropriate timing of surgical intervention after transmural acute myocardial infarction

OBJECTIVE

Recommended timing of coronary revascularization after transmural acute myocardial infarction ranges from immediate surgical intervention to repair 4 weeks after infarction. Such wide variation has created a dilemma in the management of these patients. The objective of this study was to delineate the optimal timing of revascularization after transmural acute myocardial infarction in a large and contemporary patient population.

METHODS

We performed a retrospective multicenter analysis of 32,099 patients who underwent coronary artery bypass grafting as the sole procedure after transmural myocardial infarction between 1991 and 1996 by 179 surgeons at 33 hospitals in New York State.

RESULTS

Overall hospital mortality for all patients who underwent coronary revascularization with a history of transmural myocardial infarction was 3.3%. Hospital mortality decreased with increasing time interval between revascularization and transmural acute myocardial infarction: 14.2%, 13.8%, 7.9%, 3.8%, 2.9%, and 2.7% for less than 6 hours, 6 hours to 1 day, 1 to 3 days, 4 to 7 days, 7 to 14 days, and greater than 15 days, respectively. Multivariate analyses of 43 potential risk factors suggests that revascularization within 3 days of transmural acute myocardial infarction is independently associated with mortality.

CONCLUSIONS

Coronary revascularization within 3 days of a transmural acute myocardial infarction might be an added risk for mortality. In the absence of absolute indications for emergency surgical intervention, such as structural complications and ongoing ischemia, a 3-day waiting period before surgical revascularization should be considered.

Energy-related metabolites during and after induced myocardial infarction with special emphasis on the reperfusion injury after extracorporeal circulation

In the clinical setting great efforts have been made with contradictory results to operate upon acutely myocardial ischaemic patients. The reasons for the absence of clear-cut results are not well understood nor are they scientifically explored. To resolve this problem further, we attempted to design an experimental in vivo model to mimic acute myocardial ischaemia followed by extracorporeal circulation (ECC) and reperfusion. One of the main targets of our protocol was monitoring of myocardial energy metabolism by microdialysis (MCD) during the periods of coronary occlusion (60 min), hypothermic (30 degrees C) ECC and cardioplegia (45 min), followed by reperfusion with (30 min) and without (60 min) ECC. In eight anaesthetized, open-chest pigs, myocardial lactate, pyruvate, adenosine, taurine, inosine, hypoxanthine and guanosine were sampled with MCD in both ischaemic and non-ischaemic areas. Myocardial area at risk and infarct size were quantified with the modified topographical evaluation methods. The principal finding with this experimental setup was a biphasic release pattern of lactate, adenosine, taurine, inosine, hypoxanthine and guanosine from ischaemic myocardium. Lactate levels were equally high in reperfused ischaemic and non-ischaemic myocardial tissue. Pyruvate demonstrated consistently higher values in non-ischaemic myocardium throughout the experiment. A pattern was discernible, lactate being a marker of compromised cell energy metabolism, and taurine being a marker of disturbed cell integrity. Of special interest was the increased level of pyruvate in microdialysates of non-ischaemic myocardium as compared with its ischaemic counterpart. In conclusion, we found disturbances in energy metabolism and cell integrity not only in ischaemic but also in non-ischaemic tissue during reperfusion implying that non-ischaemic myocardium demonstrated an unexpected accumulation of lactate and pyruvate. These new findings could at least partly be explicatory to the increased risk of heart surgery in connection with acute myocardial infarction.

Optimal timing of revascularization: transmural versus nontransmural acute myocardial infarction

BACKGROUND

Higher mortality for emergency coronary artery bypass grafting (CABG) after an acute myocardial infarction (AMI) is well established. Whether it applies to both transmural and nontransmural AMI is unclear. This information may have different therapeutic implications for each cohort of patients.

METHODS

A retrospective multicenter analysis of 44,365 patients who underwent CABG after myocardial infarction between 1993 and 1996 by 179 surgeons at 32 hospitals in New York State was performed.

RESULTS

Overall hospital mortality for all patients with or without AMI was 2.5% versus 3.1% for patients who underwent CABG with history of myocardial infarction. Hospital mortality decreased with increasing time interval between CABG and AMI; 11.8%, 9.5%, and 2.8% (p < 0.001 for all values) for less than 6 hours, 6 hours to 1 day, and greater than 1 day, respectively. Patients with transmural and nontransmural AMI had identical mortality of 3.1%. However, different patterns emerged when comparing these two groups of patients with respect to time of operation. Mortality was higher in the transmural group if CABG was performed within 7 days after AMI. Multivariate analysis confirmed that CABG within 1 day and 6 hours of AMI are independent risk factors for mortality in the transmural and nontransmural groups, respectively.

CONCLUSIONS

Early operation after transmural AMI has a significantly higher risk, and surgeons should be prepared to provide aggressive cardiac support including left ventricular assist devices in this ailing population. Waiting in some may be warranted.

[The practical clinical guidelines of the Sociedad Española de Cardiología on coronary surgery]

Surgery in coronary disease, including myocardial revascularization and the surgery of mechanical complications of acute myocardial infarction, has shown to improve the symptoms, quality of life and/or prognosis in certain groups of patients. The expected benefit in each patient depend on many well-known factors among which the appropriateness of the indication for surgery is fundamental. The objective of these guidelines is to review current indications for cardiac surgery in patients with coronary heart disease through an evaluation of the degree of evidence of effectiveness in the light of current knowledge (systematic review of bibliography) and expert opinion gathered from various reports. Indications and the degree of recommendation for conventional coronary artery bypass grafting have been established for each of the most frequent anatomo-clinical situations defined by clinical symptoms (stable angina, unstable angina and acute myocardial infarction) as well as by left ventricular function and extend of coronary disease. Furthermore, the subgroups with the greatest surgical risk and stratification models are described to aid the decision making process. Also we analyse the rational basis and indication for the new surgical techniques such as minimally invasive coronary surgery and total arterial revascularization. Finally, the indication and timing of surgery in patients with mechanical complications of acute myocardial infarction are considered.

Myocardial revascularisation after acute myocardial infarction

One hundred and twenty-three patients had coronary artery bypass grafting (CABG) within 30 days of acute myocardial infarction (AMI) from May 1992 to November 1997. Commonest infarct was anterior transmural (61.8%) and commonest indication of surgery was post-infarct persistent or recurrent angina (69.1%). Ten patients were operated within 48 h and 36 between 48 h to 2 weeks of having MI. Out of these, nine patients were having infarct extension and cardiogenic shock at the time of surgery. Pre-operatively fourteen patients were on inotropes of which six also had intra-aortic balloon pump (IABP) support. All patients had complete revascularisation with 3.8+/-1.2 distal anastomoses per patient. By multivariate analysis, we found that independent predictors of post-operative morbidity [inotropes >48 h, use of IABP, ventilation >24 h, ICU stay >5 days] and complications [re-exploration, arrhythmias, pulmonary complications, wound infection, cerebrovascular accident (CVA)] were left ventricular ejection fraction (LVEF) <30%, Q-wave MI, surgery <48 h after AMI, presence of pre-operative cardiogenic shock and age >60 years (P < or = 0.01). Mortality at 30 days was 3.3%. LVEF <30%, Q-wave MI, surgery <48 h after AMI, presence of pre-operative cardiogenic shock and age >60 years were found to be independent predictors of 30 days mortality (P < or = 0.01). Ninety patients were followed up for a mean duration of 33 months (1 to 65 months). There were three late deaths and five patients developed recurrence of angina. To conclude, CABG can be carried out with low risk following AMI in stable patients for post-infarct angina. Patients who undergo urgent or emergent surgery and who have pre-operative cardiogenic shock, IABP, poor left ventricular functions, age >60 years and Q-wave MI are at increased risk.

Appropriate timing of elective coronary artery bypass graft surgery following acute myocardial infarction

BACKGROUND

The appropriate timing of elective coronary artery bypass surgery (CABG) following acute myocardial infarction (AMI) remains uncertain. It is hypothesized that a waiting period allows the myocardium to recover prior to revascularization, thus decreasing morbidity and mortality. This study was designed to determine if a waiting strategy is justified following AMI in patients requiring elective CABG.

METHODS

Between 1994 and 1996, 214 patients underwent isolated, nonrepeat, elective CABG. Three groups were evaluated: group I, control, 155 patients with no AMI; group 11, 39 patients with nontransmural AMI; and Group III, 20 patients with transmural AMI. Demographics, intraoperative, and postoperative variables were collected and compared among all groups.

RESULTS

Groups were well-matched demographically: group I, patients waited an average of 2.3 days in hospital prior to operation; group II, an average of 4.2 days; and group III, an average of 5.2 days. Except for the use of inotropes, group I 34%, group 11 39%, and group III 70% (P = 0.007), and the intra-aortic balloon pump, group I 0%, group 11 8%, and group III 25% (P = 0.001). There were no differences in complications. Importantly, there was no difference in mortality or postoperative length of stay. The mortality in group I was 2.6%, in group 11 2.6%, and in group III 0%. The length of stay in groups I and II was 8.5 days, and in group III, 8.1 days.

CONCLUSION

A waiting period of 3 to 5 days after a nontransmural AMI and 5 to 7 days after a transmural AMI can produce similar postoperative results to non-AMI patients undergoing CABG. Thus, a waiting strategy to allow the myocardium to recover is justified.

Coronary revascularization surgery after myocardial infarction: impact of bypass surgery on survival after thrombolysis. GUSTO Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries

OBJECTIVES

This study sought to investigate the impact of surgical revascularization on outcome after myocardial infarction.

BACKGROUND

Small variations in rates of coronary artery bypass graft surgery (CABG) were noted among thrombolytic regimens in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) trial, prompting the question of whether survival differences were partly related to differences in CABG rates.

METHODS

Patients in the GUSTO trial were randomized to one of four thrombolytic strategies. Of 40,861 patients with complete data, 3,526 underwent surgical revascularization during their initial hospital admission. Thirty-day and 1-year mortality rates were estimated using Kaplan-Meier techniques, and the impact of CABG as a time-dependent covariate on death was evaluated using a Cox survival model, adjusting for baseline prognostic factors.

RESULTS

The median time from study enrollment to CABG was 7 days across treatment groups. A 15% reduction in mortality for the tissue-type plasminogen activator (t-PA)-treated group was evident by the seventh day. Bypass surgery was a significant independent predictor of 30-day mortality (risk ratio 1.87) and a weaker predictor of 1-year mortality (risk ratio 1.21). Operative mortality was highest in patients with acute mitral regurgitation, ventricular septal defect or poor left ventricular function and in those undergoing CABG within the first 4 days of randomization.

CONCLUSIONS

The survival benefit of accelerated t-PA was not related to surgical revascularization. Bypass surgery was associated with excess mortality in the first year, but the added short-term mortality associated with CABG may be balanced by anticipated long-term benefit in specific groups of patients.

Coronary artery bypass grafting within 30 days of an acute myocardial infarction

Risks and benefits of performing coronary artery bypass grafting (CABG) within 30 days of an acute myocardial infarction (AMI) were examined. In 642 patients operated on between January 1988 and December 1993, emergent CABG was performed in 46 patients for cardiogenic shock mainly for failed thrombolysis in patients with an evolving AMI. The remaining patients underwent urgent (< 72 hours) or elective (> 72 hours) revascularization for failed percutaneous transluminal coronary angioplasty (n = 73), postinfarction angina (n = 381), vein graft stenosis (n = 100), and complications after an AMI (n = 42). In patients who underwent primary CABG for an uncomplicated AMI, the infarct was subendocardial in 68, anterolateral or septal in 200, inferior or posteroinferior in 200, and posterolateral in 32 patients. Early mortality (< 30 days) was 5.9% for the entire series and 0%, 4.5%, 4.5%, 29%, 9%, 8%, 10%, and 26% for the subsets of patients with subendocardial infarct, anterolateral or septal infarct, inferior or posteroinferior infarct, ischemic mitral regurgitation, left ventricular aneurysm, redo CABG, age more than 70 years, and left ventricular ejection fraction less than 0.30, respectively. By multivariate analysis, independent predictors of early mortality were left ventricular ejection fraction less than 0.30, age more than 70 years, and cardiogenic shock.(ABSTRACT TRUNCATED AT 250 WORDS)