Neuroprotective Effect of Mild Hypothermia Versus Normothermia During Cardiopulmonary Bypass of Coronary Artery Surgery

Summary

In high-income countries, coronary artery bypass grafting (CABG) remains a common procedure, with approximately 36.7 operations per 100,000 inhabitants annually, corresponding to about 136,000 procedures in the European Union. This highlights the substantial healthcare burden and the need to optimize surgical outcomes. Cardiopulmonary bypass (CPB) is a fundamental component of cardiac surgery, ensuring extracorporeal perfusion of vital organs.

Hypothermic CPB has historically been widely used for organ protection due to its presumed neuroprotective mechanisms. However, evidence demonstrating its superiority over normothermic CPB remains inconclusive. In its 2024 guidelines, the European Association for Cardio-Thoracic Surgery recommends considering normothermia (≥35 °C) to reduce postoperative neurocognitive dysfunction (Class II, Level A). This recommendation is primarily based on two meta-analyses, but the underlying studies show methodological heterogeneity, outdated practices, and limited applicability to contemporary cardiac surgery. Importantly, the guidelines acknowledge the need for large randomized controlled trials to define optimal target temperature management (TTM) during CPB.

Previous diffusion-weighted MRI studies have demonstrated silent ischemic brain lesions in approximately 30% of CABG patients, with postoperative neurocognitive decline occurring in a similar proportion. However, no significant differences have been shown between normothermic and hypothermic CPB. Diffusion tensor imaging (DTI) extends conventional diffusion imaging by enabling detailed assessment of white matter microstructure and tractography. Fractional anisotropy (FA), a key DTI metric, has demonstrated prognostic value in various neurological conditions but has not yet been applied in CABG patients.

Blood-based biomarkers, including glial fibrillary acidic protein, neurofilament light chain, neuron-specific enolase, and total tau, offer complementary insights into brain injury but have not been studied in combination with DTI in this population.

This study will compare mild hypothermic (33-34 °C) and normothermic (36.5 °C) CPB to evaluate their neuroprotective effects using advanced MRI techniques and blood-based biomarkers. The primary aim is to determine whether mild hypothermia provides superior neuroprotection following CABG. Secondary objectives include assessing white matter injury evolution, global ischemic burden, associations with biomarkers and neurocognitive decline, and developing integrated prognostic models to improve outcomes in CABG patients.

Conditions

• Coronary Artery Disease
• Brain Injury

Interventions

PROCEDURE

Normothermic cardiopulmonary bypass

normothermic cardiopulmonary bypass with nasopharyngeal temperature of 36.5 ± 0.2°C

PROCEDURE

Hypothermic cardiopulmonary bypass

mild hypothermic cardiopulmonary bypass with nasopharyngeal temperature of 33 ± 0.2°C

Sponsors & Collaborators

• Turku University Hospital

  lead OTHER_GOV

Principal Investigators

• Timo Laitio, MD, PhD · Turku University Hospital, Wellbeing Services County of Southwest Finland

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-01-01

Primary Completion

2029-12-31

Completion

2029-12-31

Countries

• Finland

Study Locations