Management of perioperative myocardial ischaemia after isolated coronary artery bypass graft surgery

Safety-Net Hospital Status Is Associated With Coronary Artery Bypass Grafting Outcomes at an Urban Academic Medical Center

INTRODUCTION

Socioeconomic disparities impact outcomes after cardiac surgery. At our institution, cardiac surgery cases from the safety-net, county funded hospital (CH), which primarily provides care for underserved patients, are performed at the affiliated university hospital. We aimed to investigate the association of socioeconomic factors and CH referral status with outcomes after coronary artery bypass grafting (CABG).

METHODS

The institutional Adult Cardiac Surgery database was queried for perioperative and demographic data from patients who underwent isolated CABG between January 2014 and June 2020. The primary outcome was major adverse cardiovascular event (MACE), a composite of postoperative myocardial infarction, stroke, or death. Secondary outcomes included individual complications. Chi-square, Wilcoxon rank-sum, and logistic regression analyses were used to compare differences between CH and non-CH cohorts.

RESULTS

We included 836 patients with 472 (56.5%) from CH. Compared to the non-CH cohort, CH patients were younger, more likely to be Hispanic, non-English speaking, and be completely uninsured or require state-specific financial assistance. CH patients were more likely to have a history of tobacco and drug use, liver disease, diabetes, prior myocardial infarction, and greater degrees of left main coronary and left anterior descending artery stenosis. CH cases were less likely to be elective. The incidence of MACE was significantly higher in the CH cohort (16.3% versus 8.2%, P = 0.001). There were no significant differences in 30-d mortality, home discharge, prolonged mechanical ventilation, bleeding, sepsis, pneumonia, new dialysis requirement, cardiac arrest, or multiorgan system failure between cohorts. CH patients were more likely to develop renal failure and less likely to develop atrial fibrillation. On multivariable analysis, CH status (odds ratio 2.39, 95% confidence interval 1.25-4.55, P = 0.008) was independently associated with MACE.

CONCLUSIONS

CH patients undergoing CABG presented with greater comorbidity burden, more frequently required nonelective surgery, and are at significantly higher risk of postoperative MACE.

European Association of Cardio-Thoracic Surgery (EACTS) expert consensus statement on perioperative myocardial infarction after cardiac surgery

Cardiac surgery may lead to myocardial damage and release of cardiac biomarkers through various mechanisms such as cardiac manipulation, systemic inflammation, myocardial hypoxia, cardioplegic arrest and ischaemia caused by coronary or graft occlusion. Defining perioperative myocardial infarction (PMI) after cardiac surgery presents challenges, and the association between the current PMI definitions and postoperative outcomes remains uncertain. To address these challenges, the European Association of Cardio-Thoracic Surgery (EACTS) facilitated collaboration among a multidisciplinary group to evaluate the existing evidence on the mechanisms, diagnosis and prognostic implications of PMI after cardiac surgery. The review found that the postoperative troponin value thresholds associated with an increased risk of mortality are markedly higher than those proposed by all the current definitions of PMI. Additionally, it was found that large postoperative increases in cardiac biomarkers are prognostically relevant even in absence of additional supportive signs of ischaemia. A new algorithm for PMI detection after cardiac surgery was also proposed, and a consensus was reached within the group that establishing a prognostically relevant definition of PMI is critically needed in the cardiovascular field and that PMI should be included in the primary composite outcome of coronary intervention trials.

[Comparative analysis of in-hospital and long-term results of patients with acute dysfunction of coronary bypass grafts depending on treatment tactics]

OBJECTIVE

Comparative analysis of in-hospital and long-term mortality of patients in whom acute dysfunction of coronary bypass grafts was detected in the early postoperative period depending on conservative or surgical tactics.

MATERIAL AND METHODS

The study is a retrospective analysis of data from 8801 patients who underwent elective coronary artery bypass grafting (CABG) between 2011 and 2022 at the Federal Center for Cardiovascular Surgery (Russia, Chelyabinsk). Among them, 196 patients underwent emergency coronary artery bypass grafting due to suspected perioperative myocardial infarction in the early postoperative period. In 119 patients, dysfunction of coronary bypass grafts was detected, in 77 patients no pathological changes were found. The criteria for inclusion in the study were patients with dysfunction of coronary bypass grafts (n=119). The 1st group included patients who underwent conservative therapy (n=33), the 2nd group (n=86) included those who underwent repeated myocardial revascularization. The primary endpoint was hospital mortality, secondary endpoints were long-term mortality and adverse cardiovascular events (myocardial infarction, stroke, repeat myocardial revascularization). Patients were surveyed via telephone.

RESULTS

In-hospital mortality in the group of surgical reintervention was 8.1%, in the group of conservative treatment - 9.1% (p=0.867). According to the results of multivariate analysis, predictors of hospital mortality in patients of both groups were extracorporeal membrane oxygenation (p=0.014), time of artificial circulation (p=0.031), duration of artificial ventilation (p=0.001), number of days in intensive care (p<0.001). When analyzing long-term mortality using the Kaplan-Meier method in group 1 and group 2, no statistically significant differences were found; in the group of conservative therapy - 85±9.6 [66.2-103.7] months versus 108.2±4.8 [98.8-117.6] months in the surgery group (log-rank p=0.06). When analyzing long-term mortality from cardiovascular causes and the occurrence of adverse cardiovascular events, statistically significant differences were determined: in the group of conservative therapy - 92.5±9.3 [74.2-110.7] months versus 117.8±3.3 [111.2-124.3] months in the surgical treatment group (log-rank p=0.007) and 78.1±9.2 [60-96.3] months versus 98.9±3.9 [91.3-106.5] months (log-rank p=0.008), respectively.

CONCLUSION

In-hospital mortality was comparable between groups. Long-term mortality from cardiovascular causes and the number of adverse cardiovascular events were significantly higher in the conservative therapy group. With timely detection of acute dysfunction of coronary bypass grafts, an active surgical approach has an advantage over conservative tactics and can improve the long-term prognosis of patients.

Considerations on the Management of Acute Postoperative Ischemia After Cardiac Surgery: A Scientific Statement From the American Heart Association

Acute postoperative myocardial ischemia (PMI) after cardiac surgery is an infrequent event that can evolve rapidly and become a potentially life-threatening complication. Multiple factors are associated with acute PMI after cardiac surgery and may vary by the type of surgical procedure performed. Although the criteria defining nonprocedural myocardial ischemia are well established, there are no universally accepted criteria for the diagnosis of acute PMI. In addition, current evidence on the management of acute PMI after cardiac surgery is sparse and generally of low methodological quality. Once acute PMI is suspected, prompt diagnosis and treatment are imperative, and options range from conservative strategies to percutaneous coronary intervention and redo coronary artery bypass grafting. In this document, a multidisciplinary group including experts in cardiac surgery, cardiology, anesthesiology, and postoperative care summarizes the existing evidence on diagnosis and treatment of acute PMI and provides clinical guidance.

Successful Treatment of Whole Coronary Artery Spasm after Off-Pump Coronary Artery Bypass Grafting

Coronary artery spasm after coronary artery bypass grafting is a rare but life-threatening condition. Herein, we report the case of a 77-year-old man who received off-pump coronary artery bypass grafting. An hour after surgery, there was a sudden hemodynamic compromise due to coronary artery spasm, prompting emergent coronary angiography with extracorporeal membrane oxygenation support. Because the angiography results showed diffuse severe spasm of the entire native coronary artery, the patient was treated with an intracoronary injection of vasodilators. The patient recovered in 7 days with mechanical support, catecholamines, and vasodilators, and he was discharged on postoperative day 30. Although coronary artery spasm after off-pump coronary artery bypass surgery is a rare condition, it must be suspected when sudden circulatory collapse occurs.

Contemporary coronary artery bypass graft surgery and subsequent percutaneous revascularization

Patients who have undergone coronary artery bypass graft (CABG) surgery are susceptible to bypass graft failure and progression of native coronary artery disease. Although the saphenous vein graft (SVG) was traditionally the most-used conduit, arterial grafts (including the left and right internal thoracic arteries and the radial artery) have improved patency rates. However, the need for secondary revascularization remains common, and percutaneous coronary intervention (PCI) has become the most common modality of secondary revascularization after CABG surgery. Procedural characteristics and clinical outcomes differ considerably from those associated with PCI in patients without previous CABG surgery, owing to altered coronary anatomy and differences in conduit pathophysiology. In particular, SVG PCI carries an increased risk of complications, and operators are shifting their focus towards embolic protection strategies and complex native-vessel interventions, increasingly using SVGs as conduits to facilitate native-vessel PCI rather than pursuing SVG PCI. In this Review, we discuss the differences in conduit pathophysiology, changes in CABG surgery techniques, and the latest evidence in terms of PCI in patients with previous CABG surgery, with a particular emphasis on safety and long-term efficacy. We explore the subject of contemporary CABG surgery and subsequent percutaneous revascularization in this complex patient population.

Predictors of perioperative myocardial infarction in patients undergoing off-pump coronary artery bypass grafting

Background

Perioperative myocardial infarction (PMI) increases morbidity and mortality after off-pump coronary artery bypass grafting (CABG). The objective of the current study was to characterize patients with PMI after off-pump CABG and identify its predictors.

Results

We included 1181 patients who had off-pump CABG from 2010 to 2020; 59 patients (5%) had PMI. We compared patients with PMI to those without PMI. Patients with PMI were older (57 (25th–75th percentiles: 51–63) vs. 54 (48–60) years; P = 0.01) and had higher NYHA class (28 (47.46%) vs. 326 (29.06%): P = 0.01). The distal anastomosis time was longer in patients with PMI (28 (23–35) vs. 24 (16–30) min; P ˂ 0.001). Patients with PMI had higher postoperative low cardiac output (10 (18.18%) vs. 1 (0.1%): P ˂ 0.001), prolonged ventilation (12 (8–39) vs. 8 (6–10) h, P ˂ 0.001), ICU (71 (46–138) vs. 24 (23–42) h; P ˂ 0.001), and hospital stay (9 (6–15) vs. 7 (6–8) days; P ˂ 0.001). Mortality was significantly higher in patients with PMI (20 (33.9%) vs. 6 (0.53%); P ˂ 0.001). Older age (OR: 1.05 (95% CI: 1.01–1.1); P = 0.02), increased number of distal anastomoses (OR: 1.74 (95% CI: 1.20–2.50); P = 0.003), preoperative congestive heart failure (OR: 10.27 (95% CI: 2.58–40.95); P = 0.001), and thrombolysis within 24 h of surgery (OR: 15.34 (1.93–121.9); P = 0.01) were associated with increased PMI, while PMI was lower in male patients (OR: 0.42 (95% CI: 0.19–0.93); P = 0.03) and with higher body surface area (BSA) (OR: 0.08 (95% CI: 0.07–0.86); P = 0.04).

Conclusions

Post-off-pump CABG PMI was associated with increased morbidity and mortality. Risk factors for PMI were older age, lower BSA, females, increased distal anastomoses, preoperative heart failure, and thrombolysis.

Protamine-Induced Coronary Graft Thrombosis: A Review

Perioperative myocardial infarction is a serious complication affecting a significant portion of patients undergoing coronary artery bypass graft surgery. This may arise due to coronary graft thrombosis, a rare but potentially fatal phenomenon associated with both congenital and acquired risk factors. Multiple case reports implicate the role of protamine in the development of such thromboses. The role of protamine in facilitating the regulation of hemostasis by reversing the anticoagulant effects of heparin in patients undergoing cardiopulmonary bypass is well-recognized. However, discussion of its potential contribution to coronary graft thrombosis and mechanisms by which this may occur is lacking. Furthermore, its narrow therapeutic index and side effect profile are such that its appropriateness as a universal reversal agent to heparin requires reconsideration. This article reviews the current body of evidence regarding the use of protamine in cardiac surgery and the limited case reports pertaining to its potential role in the pathophysiology of coronary graft thrombosis.

[Peculiariities of diagnostic parameters in patients with acute myocardial lesion after coronary artery bypass grafting]

Annually, up to 850 000 coronary aortic bypass graft operations are performed worldwide. Despite modern technical equipment ensuring a high level of safety of the procedure, currently important remains a problem related to intraoperative myocardial damage in using artificial circulation. Early detection and clinical assessment of myocardial ischaemia often present a difficult task. This article deals with clinical, instrumental and laboratory methods of diagnosis, aimed at verification of an intraoperative cardiac lesion associated with graft dysfunction in coronary artery bypass grafting. Isolated electrocardiographic and echocardiographic signs of myocardial ischaemia between the comparison groups did not differ significantly. Analysing the markers of myocardial lesions, statistically significant differences were obtained only after 48 hours which, from the point of view of saving viable myocardium, is an utterly long-term interval. Studying the findings of intraoperative flowmetry showed statistically significant dependence between velocity characteristics, pulse index of shunts and their patency on angiographic examination. Thus, only combination of diagnostic parameters makes it possible to detect myocardial damage related to shunt dysfunction. This enables early determination of indications for performing bypass angiography and selection of the required therapeutic policy. Timely coronary artery angiography makes it possible to reveal defects of shunts and to timely perform surgical correction, preventing myocardial infarction.

Incessant Refractory Polymorphic Ventricular Tachycardia After Coronary Artery Bypass Graft

Polymorphic ventricular tachycardia (PVT) post coronary artery bypass (CABG) surgery is associated with acute myocardial ischemia, hemodynamic instability, and metabolic derangements. When acute ischemia is suspected, a comprehensive investigation for reversible causes is justified to improve patient outcomes. We present a curious case of incessant, refractory PVT in a patient with an unknown etiology requiring percutaneous coronary intervention (PCI) post CABG. The patient was a 73-year-old female with multiple comorbidities who presented to the hospital with anginal chest pain for one day. Initial electrocardiogram (EKG) showed sinus tachycardia with ST-segment depressions in the inferior-lateral leads. Initial cardiac troponin I was elevated at 28.280 ng/mL. Dual antiplatelet therapy and heparin were started. Urgent coronary angiography revealed significant triple-vessel disease, and she subsequently underwent three-vessel CABG. Her postoperative course was complicated by PVT refractory to all antiarrhythmic therapy and ventricular fibrillatory (VF) arrest with the recovery of spontaneous circulation after defibrillation and amiodarone bolus. Despite normal electrolytes and discontinuation of all QT-prolonging agents, PVT persisted. Urgent coronary angiography revealed a patent venous graft to a previously underappreciated severely stenotic distal segment of the left anterior descending artery (LAD). She underwent PCI of the culprit lesion with the termination of PVT. Although acute graft failure is regularly the culprit for acute myocardial infarction perioperatively, emergent coronary angiography post coronary bypass surgery revealed patent grafts and a previously underestimated severe coronary lesion contributing to ongoing ischemia. Post CABG percutaneous coronary intervention (PCI) yielded a complete resolution of her arrhythmia.

Outcome of Postcardiac Surgery Acute Myocardial Infarction and Role of Emergency Percutaneous Coronary Interventions

Background. Cardiac surgery carries a well-known risk of perioperative myocardial infarction (MI), which is associated with high morbidity and both in-hospital and late mortality. The rapid haemodynamics deterioration and presence of myocardial ischemia early after cardiac surgical operations is a complex life-threatening condition where rapid diagnosis and management is of fundamental importance. Objective. To analyse the factors associated with mortality of patients with postcardiotomy MI and to study the role of emergency coronary angiography in management and outcome. Methods. We retrospectively enrolled adult patients diagnosed to have postcardiotomy MI and underwent emergency coronary angiography at our tertiary care hospital between January 2016 and August 2019. Results. Sixty-one patients from consecutive 1869 adult patients who underwent cardiac surgeries were enrolled in our study. The studied patients had a mean age of 49 ± 16.2 years with a mean BMI of 29.5 ± 6.6 and 65.6% of them were males. As compared to the survivors group, the nonsurvivors of perioperative MI had significant preoperative CKD, postoperative AKI, longer CPB time, frequent histories of previous PCI, previous cardiotomies, pre and postoperative ECMO use, higher median troponin I levels, higher peak and 24 hours median lactate levels. Regression analysis revealed that reoperation for revascularization (OR: 23; 95% CI: 8.27–217.06; P=0.034) and hyperlactataemia (OR: 3.21; 95% CI: 1.14–9.04; P=0.027) were independent factors associated with hospital mortality after perioperative MI. Hospital mortality occurred in 25.7% vs 86.7% (P<0.001), AKI occurred in 37.1% vs 93.3% (P<0.001), haemodialysis was used in 28.6% vs 80% (P=0.002), and mediastinal exploration for bleeding was performed in 31.4% vs 80% (P=0.006) in the PCI and reoperation groups, respectively, while there were no significant differences regarding gastrointestinal bleeding, cerebral strokes, or intracerebral bleeding. The median peak troponin level was 795 (IQR 630–1200) vs 4190 (IQR 3700–6300) (P<0.001) in the PCI and reoperation groups, respectively. Absence of significant angiographic findings occurred in 18% of patients. Conclusions. Perioperative MI is associated with significant morbidities and hospital mortality. Reoperation for revascularization and progressive hyperlactataemia are independent predictors of hospital mortality. Emergency coronary angiography is helpful in diagnosis and management of perioperative MI.

Outcome of Postcardiac Surgery Acute Myocardial Infarction and Role of Emergency Percutaneous Coronary Interventions

Background. Cardiac surgery carries a well-known risk of perioperative myocardial infarction (MI), which is associated with high morbidity and both in-hospital and late mortality. The rapid haemodynamics deterioration and presence of myocardial ischemia early after cardiac surgical operations is a complex life-threatening condition where rapid diagnosis and management is of fundamental importance. Objective. To analyse the factors associated with mortality of patients with postcardiotomy MI and to study the role of emergency coronary angiography in management and outcome. Methods. We retrospectively enrolled adult patients diagnosed to have postcardiotomy MI and underwent emergency coronary angiography at our tertiary care hospital between January 2016 and August 2019. Results. Sixty-one patients from consecutive 1869 adult patients who underwent cardiac surgeries were enrolled in our study. The studied patients had a mean age of 49 ± 16.2 years with a mean BMI of 29.5 ± 6.6 and 65.6% of them were males. As compared to the survivors group, the nonsurvivors of perioperative MI had significant preoperative CKD, postoperative AKI, longer CPB time, frequent histories of previous PCI, previous cardiotomies, pre and postoperative ECMO use, higher median troponin I levels, higher peak and 24 hours median lactate levels. Regression analysis revealed that reoperation for revascularization (OR: 23; 95% CI: 8.27–217.06; P=0.034) and hyperlactataemia (OR: 3.21; 95% CI: 1.14–9.04; P=0.027) were independent factors associated with hospital mortality after perioperative MI. Hospital mortality occurred in 25.7% vs 86.7% (P<0.001), AKI occurred in 37.1% vs 93.3% (P<0.001), haemodialysis was used in 28.6% vs 80% (P=0.002), and mediastinal exploration for bleeding was performed in 31.4% vs 80% (P=0.006) in the PCI and reoperation groups, respectively, while there were no significant differences regarding gastrointestinal bleeding, cerebral strokes, or intracerebral bleeding. The median peak troponin level was 795 (IQR 630–1200) vs 4190 (IQR 3700–6300) (P<0.001) in the PCI and reoperation groups, respectively. Absence of significant angiographic findings occurred in 18% of patients. Conclusions. Perioperative MI is associated with significant morbidities and hospital mortality. Reoperation for revascularization and progressive hyperlactataemia are independent predictors of hospital mortality. Emergency coronary angiography is helpful in diagnosis and management of perioperative MI.