Myocardial infarction after cardiac surgery: When to intervene?

Central MessageSuspicion of myocardial ischemia right after cardiac surgery requires prompt clinical evaluation and transfer to the catheterization laboratory or to the operating room, if deemed necessary.See Commentaries on pages 1202 and 1203.Feature Editor's Introduction—Diagnosing myocardial infarction following cardiac surgery can be challenging. Hospitals have different activation protocols when myocardial ischemia is suspected, which ultimately aim to preserve the myocardium from further cellular loss by timely restoration of the coronary blood flow. Individual signs such as physical examination, biomarkers, and electrocardiographic changes are rather nonspecific and common after cardiac surgery and often perioperative teams are unsure about the appropriate management. This Invited Expert Opinion article by Dangas and colleagues explores the underlying etiologies, clinical evaluation, and management strategies of postoperative myocardial infarction after cardiac surgery. The authors focus on 2 specific etiologies for postoperative myocardial infarction (coronary artery bypass graft failure and injury during valvular surgery), and they center their in-depth discussion on the assessment and management of these serious adverse events.Mariya Geube, MD Suspicion of myocardial ischemia right after cardiac surgery requires prompt clinical evaluation and transfer to the catheterization laboratory or to the operating room, if deemed necessary. See Commentaries on pages 1202 and 1203. Over the past decades, cardiac surgery (CS) has undergone a rapid and remarkable development that significantly decreased complications and improved surgical outcomes. Nonetheless, myocardial infarction (MI) remains an important postoperative complication. The actual incidence of postoperative MI varies across studies (2%-10%) and is highly dependent on the definition used (ie, Third Universal Definition of MI, Fourth Universal Definition of MI, Society for Cardiovascular Angiography and Intervention definition, etc).1Thielmann M. Sharma V. Al-Attar N. Bulluck H. Bisleri G. Bunge J.J.H. et al.ESC joint working groups on cardiovascular surgery and the cellular biology of the heart position paper: peri-operative myocardial injury and infarction in patients undergoing coronary artery bypass graft surgery.Eur Heart J. 2017; 38: 2392-2407Crossref PubMed Scopus (98) Google Scholar,2Thygesen K. Alpert J.S. Jaffe A.S. Chaitman B.R. Bax J.J. Morrow D.A. et al.Fourth universal definition of myocardial infarction (2018).J Am Coll Cardiol. 2018; 72: 2231-2264Crossref PubMed Scopus (1825) Google Scholar Whereas the criteria for nonprocedure-related MI are well defined, reaching a consensus on a single definition for procedure-related MI has been challenging.2Thygesen K. Alpert J.S. Jaffe A.S. Chaitman B.R. Bax J.J. Morrow D.A. et al.Fourth universal definition of myocardial infarction (2018).J Am Coll Cardiol. 2018; 72: 2231-2264Crossref PubMed Scopus (1825) Google Scholar As patients are rarely capable of reporting the classic ischemic symptoms shortly after CS, clinicians in the intensive care (ICU) and step-down units rely mostly on diagnostic tests to establish the diagnosis of MI. In addition, high-level evidence-driven guidance is lacking, as most findings are based on observational studies and expert consensus documents (rather than any randomized study). Therefore, the management of postoperative MI in the context of CS remains a topic of ongoing debate. Hereafter, we aim to provide guidance on the management of MI in the setting of CS, mainly after coronary artery bypass and heart valve surgeries. Although the etiologies of post-CS MI are different in the aforementioned operations, the overall management approach is rather similar. Various factors can lead to myocardial injury after CS. Many of them are related to the extent of myocardial tissue damage, potential ischemic injury, and the technical aspects of the surgery inclusive of any related cardioplegia applied.3Whittaker A. Aboughdir M. Mahbub S. Ahmed A. Harky A. Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review.Perfusion. 2021; 36: 338-351Crossref PubMed Scopus (13) Google Scholar In this review, we focus on 2 common etiologies of MI after coronary and valvular surgeries. Graft dysfunction is a complex phenomenon that may rarely occur early in the postoperative period. Graft harvesting approaches, vessel selection (ie, venous vs arterial), myocardial-preservation solutions (ie, normal saline, heparinized blood, crystalloid solution, etc.), and anastomosis techniques all play a role in determining the surgical outcome. Graft failure is usually due to thrombotic occlusion, anastomotic stenosis, bypass graft kinking, overstretching, or vasoconstriction. Radial artery conduits are particularly prone to spasm due to adrenergic receptors' dominance in the underlying vascular smooth muscle and decreased endothelial nitric oxide synthase expression. Moreover, perioperative vasopressor use may extend several days in the ICU/step-down unit and may affect graft flow after coronary artery bypass graft (CABG) surgery. Another essential factor to consider is the surgical approach used, such as on-pump or off-pump coronary artery bypass. Several studies reveal greater graft patency and more complete revascularization after on-pump coronary artery bypass.4Alberti K.G.M.M. Eckel R.H. Grundy S.M. Zimmet P.Z. Cleeman J.I. Donato K.A. et al.Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation task force on epidemiology and prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity.Circulation. 2009; 120: 1640-1645Crossref PubMed Scopus (10478) Google Scholar However, surgeon experience, conduit selection, and postoperative anticoagulation allow safe off-pump coronary artery bypass in selected patients.5Lamy A. Devereaux P.J. Prabhakaran D. Taggart D.P. Hu S. Paolasso E. et al.Off-pump or on-pump coronary-artery bypass grafting at 30 days.N Engl J Med. 2012; 366: 1489-1497Crossref PubMed Scopus (549) Google Scholar,6Puskas J.D. Williams W.H. Mahoney E.M. Huber P.R. Block P.C. Duke P.G. et al.Off-pump vs conventional coronary artery bypass grafting: early and 1-year graft patency, cost, and quality-of-life outcomes: a randomized trial.JAMA. 2004; 291: 1841-1849Crossref PubMed Scopus (491) Google Scholar Coronary stenosis/occlusion resulting in acute ischemia is a rare but well-reported complication of valvular surgery.7Coutinho G.F. Leite F. Antunes M.J. Circumflex artery injury during mitral valve repair: not well known, perhaps not so infrequent-lessons learned from a 6-case experience.J Thorac Cardiovasc Surg. 2017; 154: 1613-1620Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar The injury mechanisms are numerous (ie, distortion, twisting, or laceration of the coronary artery), but most are related to surgical stitch placement. For example, stenosis of the left circumflex artery, especially in left-dominant coronary artery circulation, occurs during mitral valve repair due to its proximity to the mitral annulus where the suture is fixed. The annulus may be 5 mm or less from the left circumflex artery (Figure 1) and can frequently be visualized by advanced intraoperative echocardiography. In this setting, ischemia may lead to significant hemodynamic compromise. Similarly, the right coronary artery can be injured or occluded during tricuspid valve repair with both suture and ring annuloplasty. The right coronary artery closely approximates the tricuspid annulus, especially in the cavotricuspid isthmus in the lower right atrium (Figure 2). A thorough understanding of the anatomic relationship between coronary and valvular anatomy is critical to minimizing these types of complications during CS.8Caruso V. Sabry H. Birdi I. Dramatic resolution of an immediate postoperative distortion of the circumflex artery during mitral valve surgery.J Card Surg. 2020; 35: 1135-1137Crossref PubMed Scopus (2) Google ScholarFigure 2Tricuspid valve annulus and the right coronary artery (RCA). The encircled area (in red) represents the region in which the right coronary artery is closest to the tricuspid annulus. APc, Anteroposterior commissure; AL, anterior leaflet; PL, posterior leaflet; ASc, anteroseptal commissure; SL, septal leaflet; PSc, posteroseptal commissure.Figure adapted from Calafiore AM, Iacò AL, Bartoloni G, Di Mauro M. Right coronary occlusion during tricuspid band annuloplasty. J Thorac Cardiovasc Surg. 2009;138:1443-4.View Large Image Figure ViewerDownload Hi-res image Download (PPT) An uncommon but important cause of post-CS MI is coronary ostial stenosis following a combined valve–graft replacement of the aortic root (also known as the Bentall procedure). Extrinsic compression or distortion of the replanted coronary neo-ostium may result in vessel occlusion and subsequent MI in the early postoperative period. Cabrol grafts to the proximal right coronary artery and the left main arteries is another surgical option that allows coronary perfusion from a very high plane relative to the aortic valve, thereby facilitating future valve procedures but also avoiding stretching/kinking of the proximal native coronary arteries.9Cabrol C. Pavie A. Gandjbakhch I. Villemot J.P. Guiraudon G. Laughlin L. et al.Complete replacement of the ascending aorta with reimplantation of the coronary arteries: new surgical approach.J Thorac Cardiovasc Surg. 1981; 81: 309-315Abstract Full Text PDF PubMed Google Scholar Common ischemic symptoms, such as angina and shortness of breath, are not typically evaluable in intubated and sedated patients in ICU. A thorough evaluation of the patient's hemodynamic status should serve as a starting point when myocardial ischemia is suspected. Whenever possible, invasive hemodynamic monitoring with a pulmonary artery catheter should be considered, as increased filling pressures may be highly suggestive of MI. Other Swan-Ganz catheter (Edwards Lifesciences, Irvine, Calif)–derived data, such as cardiac output measurement, may also indicate the loss of viable myocardium and impairment in global cardiac function. However, all findings should be interpreted with caution, given the many coexisting postoperative conditions. For example, persistent hypotension requiring vasopressors is common following CS due to vasoplegia induced by prolonged cardiopulmonary bypass or cardiogenic shock and exacerbated by reduced preload or anesthetic medications. Similarly, elevated lactate levels in the ICU are common and represent an oxygen supply–consumption mismatch or impaired lactate clearance. However, this may be secondary to several postoperative etiologies (ie, hypoxemia, hyperglycolysis, hypovolemia, anemia, and liver injury) and not specific for coronary ischemia.10O'Connor E. Fraser J. The interpretation of perioperative lactate abnormalities in patients undergoing cardiac surgery.Anaesth Intensive Care. 2012; 40: 598-603Crossref PubMed Google Scholar Cardiac biomarkers play an essential role in detecting myocardial injury and have become critical in diagnosing MI. However, elevation in cTn levels is a common laboratory finding after cardiac surgery due to direct injury to the myocardium. As a result, identifying clinically significant increases in cTn that necessitate further investigation remains challenging. According to the Fourth Universal Definition of MI, type 5 MI (also known as CABG-related MI) is defined as a cTn level increase of at least 10 times the 99th percentile upper reference limit in patients with normal baseline cTn values.2Thygesen K. Alpert J.S. Jaffe A.S. Chaitman B.R. Bax J.J. Morrow D.A. et al.Fourth universal definition of myocardial infarction (2018).J Am Coll Cardiol. 2018; 72: 2231-2264Crossref PubMed Scopus (1825) Google Scholar In those with elevated baseline cTn and in whom cTn levels are stable or decreasing, the postprocedure cTn must increase by at least 20%. However, the absolute postprocedural value still must be more than 10 times the 99th percentile upper reference limit. Creatine kinase isoenzyme makes a steeper upstroke/decline over 24 hours (than the several days of the cTn curve) and therefore easier to assess a subsequent re-elevation. As no cTn cut-off values specific for valvular surgery have been established, the aforementioned mentioned values could be taken as reference when evaluating such patients.11Cubero-Gallego H. Lorenzo M. Heredia M. Gómez I. Tamayo E. Diagnosis of perioperative myocardial infarction after heart valve surgery with new cut-off point of high-sensitivity troponin T and new electrocardiogram or echocardiogram changes.J Thorac Cardiovasc Surg. 2017; 154: 895-903Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar Whenever the aforementioned conditions are met, electrocardiogram (ECG) and noninvasive imaging should be used in parallel to increase the sensitivity and specificity for the diagnosis of MI. Prolonged isolated elevation of cardiac biomarkers, unaccompanied by electrocardiographic or imaging findings, indicates procedure-related myocardial injury (ie, cardioplegia and reperfusion injury) that is typically not amenable to invasive management.1Thielmann M. Sharma V. Al-Attar N. Bulluck H. Bisleri G. Bunge J.J.H. et al.ESC joint working groups on cardiovascular surgery and the cellular biology of the heart position paper: peri-operative myocardial injury and infarction in patients undergoing coronary artery bypass graft surgery.Eur Heart J. 2017; 38: 2392-2407Crossref PubMed Scopus (98) Google Scholar Therefore, additional diagnostic testing is of limited value when the patient is in stable condition. All patients undergoing CS usually have a baseline ECG followed by serial postoperative ECG tracings. While ECG changes following CS are frequent and may be associated with postoperative ischemia, they are often nonspecific and benign. ST-segment and T-wave changes are common after CS because of pericardial and epicardial injury and thus are nonspecific indicators of MI postoperatively. However, specific ECG patterns, such as ST-segment elevation with reciprocal ST-depression, represent more reliable indicators of ischemia that require further noninvasive investigation (ie, cardiac biomarkers and echocardiography) before transferring the patient to the catheterization laboratory or back to the operating room.2Thygesen K. Alpert J.S. Jaffe A.S. Chaitman B.R. Bax J.J. Morrow D.A. et al.Fourth universal definition of myocardial infarction (2018).J Am Coll Cardiol. 2018; 72: 2231-2264Crossref PubMed Scopus (1825) Google Scholar In contrast, development of new pathologic Q waves coupled with a significant rise in cardiac biomarkers (not necessarily more than 10 times the 99th percentile upper reference limit) represent the strongest evidence that prompts angiographic evaluation to rule out graft or native coronary artery occlusion.2Thygesen K. Alpert J.S. Jaffe A.S. Chaitman B.R. Bax J.J. Morrow D.A. et al.Fourth universal definition of myocardial infarction (2018).J Am Coll Cardiol. 2018; 72: 2231-2264Crossref PubMed Scopus (1825) Google Scholar The appearance of a new persistent left bundle branch block (LBBB) on ECG is another strong marker of an ischemic event. However, in the setting of valvular surgery, we recommend the interpretation of this finding with caution, as LBBB commonly develops after valve replacement surgery.12Généreux P. Piazza N. Alu M.C. Nazif T. Hahn R.T. et al.VARC-3 Writing CommitteeValve academic research consortium 3: updated endpoint definitions for aortic valve clinical research.Eur Heart J. 2021; 42: 1825-1857Crossref PubMed Scopus (202) Google Scholar Ventricular arrhythmias following CS most often are due to metabolic and electrolyte abnormalities, catecholaminergic medications, reperfusion injury, scar tissue, and perioperative MI. In the setting of ventricular tachycardia/ventricular fibrillation, the priority is urgent resuscitation, including defibrillation and correction of reversible causes of arrhythmia (ie, hyperkalemia, hypomagnesemia, and acidosis). The gravity of all the aforementioned findings increases when hemodynamic instability and elevated lactate level coexist. Echocardiography is a powerful tool that enables the evaluation of ventricular and valvular function and the detection of myocardial dysfunction caused by regional or global ischemia. It is usually performed when results from biomarker testing and ECG are inconclusive, a common occurrence in postoperative MI cases. Regional wall motion abnormalities can be detected on echocardiography with direct correlation to the acute coronary occlusion territory. They depict decreases in amplitude and rate of myocardial contractility, as well as myocardial thickening and local remodeling. Nonetheless, regional wall motion abnormalities alone do not necessarily indicate acute ischemia, as they can be due to previous infarction, myocarditis, LBBB, or cardiomyopathy. They can also be related to ventricular pacing, inflammation, stunning, or hibernation post-CS.1Thielmann M. Sharma V. Al-Attar N. Bulluck H. Bisleri G. Bunge J.J.H. et al.ESC joint working groups on cardiovascular surgery and the cellular biology of the heart position paper: peri-operative myocardial injury and infarction in patients undergoing coronary artery bypass graft surgery.Eur Heart J. 2017; 38: 2392-2407Crossref PubMed Scopus (98) Google Scholar To localize and quantify the extent of an infarct, contrast echocardiography is recommended as it enhances visualization of all myocardial segments perfused by different native coronary arteries or bypass grafts.13Cerqueira M.D. Weissman N.J. Dilsizian V. Jacobs A.K. Kaul S. Laskey W.K. et al.Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart: a statement for healthcare professionals from the cardiac imaging committee of the council on clinical cardiology of the American Heart Association.Circulation. 2002; 105: 539-542Crossref PubMed Scopus (5450) Google Scholar Notwithstanding, echocardiographic findings of global biventricular dysfunction, with or without regional variation, may be detected. Such observations may occur in the setting of a single or multiple graft failure to large coronary artery territories. In addition, they can be attributed to cardioplegia and other cardiac surgery-related physiologic changes that are not related to graft or native artery occlusion. While the decision to intervene is under evaluation among the surgical and ICU teams, maintenance of the hemodynamic status and vital signs is of utmost importance. In patients with suspected postoperative ischemia, myocardial oxygen delivery should be optimized by increasing supply and decreasing demand. Although supplemental oxygen may not reduce mortality in patients without hypoxemia, oxygen should be supplied to preserve a greater than 90% saturation. Coronary perfusion pressure is maintained with vasopressors ahead of any consideration for ventricular unloading with any support device; tachycardia is minimized by avoiding sympathetic stimulation and providing appropriate analgesia. Review of hemodynamic data, ECG findings, and bedside echocardiography should be done to rule out nonischemic causes of hemodynamic instability before considering percutaneous or surgical intervention (Figure 3). In absence of strong evidence from diagnostic tests besides cTn increases, watchful waiting with repeated testing (ie, serial measures of cardiac biomarkers and re-evaluation with electrocardiography and echocardiography) is preferred whenever the patient shows significant improvement in hemodynamic parameters. Conversely, when the suspicion for MI is high based on all the aforementioned intertwined factors, 2 main management options are possible: transfer to the operating room for surgical re-exploration without a clear diagnosis or transfer to the catheterization laboratory for further diagnostic workup with coronary angiography. The former is mandatory for hemorrhagic emergencies and when a patient is in severe hemodynamic compromise despite all measures. Whenever the hemodynamic status permits, transfer to the catheterization is warranted. Coronary angiography is the gold standard for diagnosing postoperative MI (whether due to graft failure or coronary artery injury during valvular surgery), as it enables prompt implementation of optimal corrective measures that limit the extent of myocardial injury. While echocardiography can be performed at the bedside, angiography requires transfer to the cardiac catheterization laboratory, which may be difficult or dangerous in critically ill patients. In addition, the risk of contrast-associated nephropathy must be weighed against the benefits the procedure.14Mehran R. Dangas G.D. Weisbord S.D. Contrast-associated acute kidney injury.N Engl J Med. 2019; 380: 2146-2155Crossref PubMed Scopus (289) Google Scholar Following coronary angiography, most patients with an indication for repeat revascularization undergo percutaneous coronary intervention (PCI) with stenting.15Alqahtani F. Ziada K.M. Badhwar V. Sandhu G. Rihal C.S. Alkhouli M. Incidence, predictors, and outcomes of in-hospital percutaneous coronary intervention following coronary artery bypass grafting.J Am Coll Cardiol. 2019; 73: 415-423Crossref PubMed Scopus (15) Google Scholar Besides the logistical reasons (ie, it is faster to perform percutaneous revascularization while the patient is already in the catheterization laboratory), repeat CS is not optimal, since many patients who develop postoperative MI are very high-risk candidates for immediate repeat CS. Long-term prognosis after such dramatic complication is guarded regardless of the treatment approaches.16Parasca C.A. Head S.J. Milojevic M. Mack M.J. Serruys P.W. Morice M.-C. et al.Incidence, characteristics, predictors, and outcomes of repeat revascularization after percutaneous coronary intervention and coronary artery bypass grafting: the SYNTAX trial at 5 years.JACC Cardiovasc Interv. 2016; 9: 2493-2507Crossref PubMed Scopus (72) Google Scholar In case of graft failure, revascularization with PCI should be first considered in native vessels supplying ischemic myocardial tissue rather than in the occluded grafts.17Levine G.N. Bates E.R. Blankenship J.C. Bailey S.R. Bittl J.A. Cercek B. et al.2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines and the Society for Cardiovascular Angiography and Interventions.J Am Coll Cardiol. 2011; 58: e44-e122Crossref PubMed Scopus (1988) Google Scholar When coronary injury after valvular surgery is suspected postoperatively, PCI can be a valid option if arterial kinking is noted on coronary angiography. Conversely, in case of coronary artery occlusion due to total extrinsic obstruction, emergent reoperation should be preferred. In case of the Bentall procedure, ischemia can be managed with immediate surgical reintervention to identify the mechanical obstruction and reposition the coronary button or bypass grafting. Shared decision-making involving intensivists, cardiac surgeons, and interventional cardiologists is of paramount importance in all the aforementioned evaluations and decisions. Antithrombotic therapy may be initiated early after CS if the bleeding risk is deemed acceptable by the medical team. Assessment of the bleeding risk is performed on individual basis while accounting for various baseline risk factors: old age, low body mass index, active bleeding (ie, primarily through the chest tubes or in the pericardium), previous major bleeding, large volumes of intraoperative salvaged cells transfused, multiple coronary anastomoses, severe hepatic failure (international normalized ratio >1.5), severe renal failure (creatinine clearance <30 mL/min), thrombocytopenia, and uncontrolled systemic hypertension.18Vuylsteke A. Pagel C. Gerrard C. Reddy B. Nashef S. Aldam P. et al.The Papworth bleeding risk score: a stratification scheme for identifying cardiac surgery patients at risk of excessive early postoperative bleeding.Eur J Cardiothorac Surg. 2011; 39: 924-930Crossref PubMed Scopus (106) Google Scholar The optimal antithrombotic strategy after CS is beyond the scope of this paper; nonetheless, the entire team of ICU, surgery, and cardiology doctors should have a detailed understanding of the key options available (Table 1) to be able to select the most beneficial and flexible strategy in the very tenuous period early post-CS. To summarize, oral antiplatelet therapy consisting of aspirin with or without a P2Y12 inhibitor (clopidogrel, prasugrel, or ticagrelor) is recommended after CABG surgery, yet patients may not be able to swallow or absorb them early post-CS. In contrast, bridging with heparin while vitamin K antagonist therapy is being initiated is typically recommended after valvular surgery (again with few days delay, as mentioned previously). The time of initiation of antithrombotic therapy and the type of antithrombotic agents used influence the decision on whether to intervene and the type of intervention (surgical vs percutaneous). If the antithrombotic therapy has been initiated and the likelihood of an ischemic event is high, coronary angiography followed by PCI may be preferred over surgery to avoid lethal bleeding complications. In certain circumstances, such as ischemia due to mechanical obstruction after valvular procedure, surgical intervention may be the only option, and the ischemic risks outweigh the bleeding risks. In contrast, when no antithrombotic agent has been administered, aspirin may be given if the patient is at low bleeding risk. Other agents, such as P2Y12 inhibitors and heparin, should be avoided until a clear diagnosis is established. An intravenous P2Y12 inhibitor infusion may allow early reversal in case of hemorrhage.Table 1Pharmacologic and clinical considerations of commonly used antithrombotic agentsRouteMechanism of actionTime to onsetHalf-lifeActivity delayed in MI/shockTime to effect reversalReversible antithrombotic activity?AspirinOralPlatelet COX-1 enzyme inhibitor20 min (when chewed)20 min (3-10 hours—dose-dependent for active metabolite)Yes4 dYesClopidogrelOralPlatelet P2Y12 receptor inhibitor2 h30 min∗Half-life is that of active metabolite.Yes5 dYesTicagrelorOralPlatelet P2Y12 receptor inhibitor30 min-1 h9 h∗Half-life is that of active metabolite.Yes4-5 dNoPrasugrelOralPlatelet P2Y12 receptor inhibitor30 min7 h∗Half-life is that of active metabolite.Yes5-9 dYesCangrelorIntravenousPlatelet P2Y12 receptor inhibitor2 min3-6 minNo30 min–1 hourN/A†Reversal with platelet transfusion is clinically insignificant given the rapid reversal of action with drug discontinuation.EptifibatideIntravenousPlatelet GP IIb/IIIa receptor inhibitor<1 h2.5 hNo3-4 hNoTirofibanIntravenousPlatelet GP IIb/IIIa receptor inhibitor30 min2.5 hNo4-8 hNoUnfractionated heparin‡Many compounds with variable molecular chains are included in these drug formulations.IntravenousBlocks thrombin generation and activity2-4 h‡Many compounds with variable molecular chains are included in these drug formulations.30 min-2 h‡Many compounds with variable molecular chains are included in these drug formulations.No (inactive against clot-bound thrombin)2-4 h‡Many compounds with variable molecular chains are included in these drug formulations.YesBivalirudinIntravenousDirect thrombin inhibitorImmediate30 minNo1.5 hNoThe pharmacokinetic/pharmacodynamic data may vary among different commercial formulations of each drug. MI, Myocardial infarction; N/A, not available.∗ Half-life is that of active metabolite.† Reversal with platelet transfusion is clinically insignificant given the rapid reversal of action with drug discontinuation.‡ Many compounds with variable molecular chains are included in these drug formulations. Open table in a new tab The pharmacokinetic/pharmacodynamic data may vary among different commercial formulations of each drug. MI, Myocardial infarction; N/A, not available. Gastrointestinal complications after CS are not uncommon and narrow the options for oral drug administration.19Chaudhry R. Zaki J. Wegner R. Pednekar G. Tse A. Sheinbaum R. et al.Gastrointestinal complications after cardiac surgery: a nationwide population-based analysis of morbidity and mortality predictors.J Cardiothorac Vasc Anesth. 2017; 31: 1268-1274Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar Indeed, anticoagulant and antiplatelet agents in these patients must be given intraoperatively in the intravenous formulation. Cangrelor, a potent intravenous P2Y12 platelet receptor inhibitor with a rapid onset of action and fast clearance from the body, is especially useful in this population. In addition, this drug's unique pharmacokinetic properties offer advantages over oral P2Y12 receptor inhibitors given the high risk of bleeding in the early postoperative period (ie, ongoing chest tube drain, fresh wound, etc) and the inability to reverse the latter options. Improvements in surgical techniques over the last several decades have resulted in treatment of increasingly complex cardiac diseases. Nonetheless, postoperative MI remains a common complication that is difficult to manage in the absence of strong evidence and guidelines. Clinical evaluation with a focused physical examination, ECG, and noninvasive imaging is warranted to decide on whether to proceed with coronary angiography or reoperation. Additional studies are needed to investigate the utility of new imaging technologies and high-sensitivity troponin assays on the diagnosis of post-CS MI.