Myocardial inflammation, injury and infarction during on-pump coronary artery bypass graft surgery

Shirjel R. Alam*, Colin Stirrat, Nick Spath, Vipin Zamvar, Renzo Pessotto, Marc R. Dweck, Colin Moore, Scott Semple, Ahmed El-Medany, Divya Manoharan, Nicholas L. Mills, Anoop Shah, Saeed Mirsadraee, David E. Newby, Peter A. Henriksen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Myocardial inflammation and injury occur during coronary artery bypass graft (CABG) surgery. We aimed to characterise these processes during routine CABG surgery to inform the diagnosis of type 5 myocardial infarction.

Methods: We assessed 87 patients with stable coronary artery disease who underwent elective CABG surgery. Myocardial inflammation, injury and infarction were assessed using plasma inflammatory biomarkers, high-sensitivity cardiac troponin I (hs-cTnI) and cardiac magnetic resonance imaging (CMR) using both late gadolinium enhancement (LGE) and ultrasmall superparamagnetic particles of iron oxide (USPIO).

Results: Systemic humoral inflammatory biomarkers (myeloperoxidase, interleukin-6, interleukin-8 and c-reactive protein) increased in the post-operative period with C-reactive protein concentrations plateauing by 48 h (median area under the curve (AUC) 7530 [interquartile range (IQR) 6088 to 9027] mg/L/48 h). USPIO-defined cellular myocardial inflammation ranged from normal to those associated with type 1 myocardial infarction (median 80.2 [IQR 67.4 to 104.8]/s). Plasma hs-cTnI concentrations rose by >= 50-fold from baseline and exceeded 10-fold the upper limit of normal in all patients. Two distinct patterns of peak cTnI release were observed at 6 and 24 h. After CABG surgery, new LGE was seen in 20% (n = 18) of patients although clinical peri-operative type 5 myocardial infarction was diagnosed in only 9% (n = 8). LGE was associated with the delayed 24-h peak in hs-cTnI and its magnitude correlated with AUC plasma hs-cTnI concentrations (r = 0.33, p <0.01) but not systemic inflammation, myocardial inflammation or bypass time.

Conclusion: Patients undergoing CABG surgery invariably have plasma hs-cTnI concentrations > 10-fold the 99th centile upper limit of normal that is not attributable to inflammatory or ischemic injury alone. Peri-operative type 5 myocardial infarction is often unrecognised and is associated with a delayed 24-h peak in plasma hs-cTnI concentrations.

Original languageEnglish
Article number115
Number of pages10
JournalJournal of cardiothoracic surgery
Volume12
DOIs
Publication statusPublished - 16 Dec 2017

Keywords

  • CABG
  • Troponin
  • Inflammation
  • Type 5
  • Myocardial infarction
  • CARDIAC TROPONIN-I
  • CARDIOPULMONARY BYPASS
  • IRON-OXIDE
  • REPERFUSION
  • TRIAL

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