Nosocomial Pneumonia After Coronary Artery Bypass Grafting

RESEARCH RELEVANCE Cardiovascular diseases (CVD), remain the leading cause of death worldwide. In 2017, mortality from cardiovascular diseases reached 862,895 people, or 587.6 per 100,000 of the population. Coronary artery disease (CAD) holds the leading position in the structure of causes of death from CVD. The annual mortality rate from CAD is 27%, with 42% of all deceased being of working age. Myocardial revascularization is one of the most common surgical procedures for the effective treatment of CAD. In the United States, over 200,000 coronary artery bypass grafting (CABG) surgeries are performed annually, with approximately 14% of patients being rehospitalized within 30 days after discharge and another 10% visiting emergency departments due to surgery-related complications and care issues. Pulmonary complications, primarily pneumonia (3%-42%), account for a significant proportion of the complications. Although pneumonia primarily affects the lungs, growing evidence suggests that it can have a negative impact on many systems and organs, particularly the cardiovascular system. The impact of pneumonia on the starting CVD consist the most evidences. The short-term and long-term impact of nosocomial pneumonia (NP) on the course of determined CVD, especially following myocardial revascularization performed using coronary bypass grafting (CABG) has not been previously assessed, and potential mechanisms have not been studied. It is known that the CABG leads to an enhanced systemic inflammatory response, is associated with nitric oxide deficiency, endothelial dysfunction, and procoagulant activity. Therefore, a postoperative complication in the form of NP in patients with multivessel CAD and not rare anatomic and functional myocardial disorders could potentially lead to a short-term additive enhancement of the inflammatory and endothelial response associated with the surgery, and to long-term activation of immune inflammation after CABG. The consequence of this may be an increased frequency of any complications within one year or more after surgery and a reduction in its effectiveness in reversing signs of coronary and heart failure. However, there is no confirmation of this assumption. The impact of pneumonia complications, such as respiratory failure, on the course of stable CAD is also insufficiently studied.

The study will be conducted at the Cardiology Research Institute - a branch of the Federal State Budgetary Scientific Institution "Tomsk National Research Medical Center of the Russian Academy of Sciences" (Cardiology Research Institute of the Tomsk NRMC) in Tomsk, Russia, from December 2024 to June 2027. The study was approved by the Biomedical Ethics Committee of the Cardiology Research Institute of the Tomsk NRMC on December 25, 2024. Informed consent will be obtained from all study participants after the nature, purpose, and potential risks of the study have been explained to them.

PRIMARY OBJECTIVE To test the hypothesis that in patients with stable coronary artery disease undergoing CABG, the occurrence of postoperative nosocomial pneumonia is associated with an adverse cardiopulmonary prognosis for at least one year after surgery.

SRCONDARY OBJECTIVES To compare the clinical, cellular, secretory, and instrumental profiles, as well as their in-hospital dynamics, between patients with an uncomplicated postoperative course and those complicated by nosocomial pneumonia.

To assess the sensitivity, specificity, and diagnostic accuracy of pulmonary and systemic criteria for diagnosing nosocomial pneumonia in patients with CAD following surgical myocardial revascularization; to identify the most specific systemic diagnostic criteria or propose new ones.

In a prospective one-year follow-up study of patients with CAD corrected by CABG, to evaluate the impact of nosocomial pneumonia on cardiopulmonary prognosis; to identify in-hospital predictors of an unfavorable prognosis for the purpose of personalized prevention.

The effectiveness of the study will be assessed by such a concept as "end point".

The primary endpoint was assessed at visits 5, 6, and 7 as the difference in parameters between the groups with pneumonia and without pneumonia and included the frequency of occurrence of one or more cardiovascular and/or respiratory endpoint events.

Inclusion criteria

• Age 18 years and older.
• Myocardial revascularization for CAD via CABG during the current hospitalization, in accordance with the indications defined by the ESC/EACTS Guidelines on Myocardial Revascularization [DOI: 10.1093/eurheartj/ehy394].
• Successful transfer from the intensive care unit to a general ward after surgery.
• One or more of the risk factor for nosocomial pneumonia [doi: 10.15829/1560-4071-2024-6094].
• Signed informed consent for participation in the study.

Pre-operative Exclusion Criteria:

• Acute coronary syndrome within the last 1 month.
• Combined surgical intervention for infective endocarditis.
• Combined valve surgery.
• Concomitant pulmonary disease requiring respiratory support prior to surgery.
• Presence of a tracheostomy.
• Participation in another clinical trial at the time of potential inclusion or within the preceding 3 months.
• Diagnosis of malignant neoplasms within the last 5 years.
• Life duration of less than 1 year.
• HIV infection.

Peri-operative Exclusion Criteria:

• Ventilator-Associated Pneumonia (VAP).
• Acute Myocardial Infarction after CABG and before inclusion.
• Acute Stroke after CABG and before inclusion.
• Pulmonary after CABG and before inclusion.
• Pulmonary Edema after CABG and before inclusion.
• Acute Respiratory Distress Syndrome (ARDS) after CABG and before inclusion.
• Pneumothorax requiring drainage after CABG and before inclusion.
• Delirium after CABG and before inclusion.
• Chronic Kidney Disease (CKD) Stage 4-5 / Acute Kidney Injury requiring renal replacement therapy or chronic dialysis.
• Any perioperative complication requiring the patient's return to the intensive care unit or prolonging the ICU stay beyond 48 hours.
• Any other active infectious process at a different site.
• Novel Coronavirus Infection (COVID-19).