A Phase 4 interventional study of Adenoseine and Placebo (sterile distilled water) in Myocardial Protection, sponsored by Hospital Nossa Senhora da Conceicao. Not yet recruiting at 1 site in Brazil. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-02-23.
Sponsored by Hospital Nossa Senhora da Conceicao · Phase 4, Interventional, and Treatment
The goal of this clinical trial is to evaluate whether the addition of adenosine to standard cardioplegia improves myocardial protection in adult patients undergoing on-pump cardiac surgery. The study population includes adult patients of both sexes undergoing elective cardiac procedures requiring cardiopulmonary bypass and cardioplegic arrest.
The main questions this trial aims to answer are:
Does the addition of adenosine to cardioplegia affect myocardial protection as assessed by transesophageal echocardiography (TEE)?
What is the effect of adenosine on biochemical markers of myocardial injury, such as postoperative high-sensitivity troponin levels?
What is the effect of adenosine on perioperative hemodynamic support requirements, as quantified by the Vasoactive-Inotropic Score (VIS)?
Researchers will compare patients receiving adenosine-supplemented cardioplegia with those receiving standard cardioplegia (placebo) to assess differences in echocardiographic indicators of myocardial protection, biomarker release, and need for vasoactive/inotropic support.
Participants will:
Receive either adenosine-supplemented cardioplegia (adenosine 1.2 mmol/L; 24 mg) or placebo according to randomization.
Undergo standard perioperative monitoring during cardiac surgery.
Undergo intraoperative transesophageal echocardiography (TEE) to evaluate myocardial protection by comparing pre- and post-cardiopulmonary bypass (CPB) measurements.
Have postoperative laboratory testing for high-sensitivity troponin at baseline, 2h, 12h, and 24h after clamp release.
Have hemodynamic support requirements recorded and VIS calculated at the end of surgery and at 12h and 24h postoperatively.
Be followed for perioperative clinical outcomes including arrhythmias, need for cardioversion or mechanical circulatory support, ICU/hospital length of stay, myocardial infarction, and mortality.
Myocardial ischemia-reperfusion injury remains a key contributor to postoperative myocardial dysfunction and adverse outcomes in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Despite refinements in cardioplegic solutions and perfusion strategies, biochemical evidence of myocardial injury and transient or persistent ventricular dysfunction remain common, particularly among older patients and those with preexisting ventricular impairment. These observations underscore the ongoing need for adjunctive strategies that enhance myocardial protection during both the ischemic arrest and early reperfusion phases.
Adenosine is an endogenous purine nucleoside with pleiotropic cardioprotective properties, including negative chronotropic and dromotropic effects, coronary vasodilation, attenuation of calcium influx, and modulation of inflammatory and endothelial pathways. Experimental data and small clinical studies suggest that adenosine administration at the onset of ischemia or during early reperfusion may reduce ischemia-reperfusion injury by facilitating rapid electrical arrest, limiting intracellular calcium overload, improving microvascular perfusion, and attenuating inflammatory activation. However, the optimal timing, dosing strategy, and clinical relevance of adenosine administration as an adjunct to modern cardioplegia in routine adult cardiac surgery remain incompletely defined.
This prospective, randomized, double-blind, placebo-controlled, parallel-group trial is designed to evaluate whether a single bolus of adenosine administered immediately after aortic cross-clamping and immediately before infusion of standard del Nido cardioplegia improves myocardial protection in adult patients undergoing elective coronary artery bypass grafting and/or valve surgery with CPB. Following cross-clamp application, patients allocated to the intervention group will receive adenosine at a concentration of 1.2 mmol/L (total dose 24 mg) delivered into the aortic root, while control patients will receive an equivalent volume of sterile water. Thereafter, cardioplegia delivery and all subsequent intraoperative management will proceed according to institutional standards, ensuring that the only protocolized difference between groups is the administration of adenosine or placebo.
Randomization will be performed using permuted blocks to ensure balanced group allocation. Blinding will be maintained for patients, surgeons, anesthesiologists, perfusionists, investigators, outcome assessors, and data analysts throughout the study period. Anesthesia management, CPB strategy, myocardial protection techniques, and postoperative care will follow standardized institutional protocols to minimize confounding.
The extent of myocardial injury will be assessed primarily through serial measurements of high-sensitivity cardiac troponin T obtained preoperatively and at predefined intervals following aortic cross-clamp removal. Hemodynamic support requirements will be quantified using the vasoactive-inotropic score (VIS), providing an integrated assessment of postoperative circulatory support needs. In addition to biochemical and hemodynamic endpoints, myocardial protection will be directly evaluated using transesophageal echocardiography (TEE). Comprehensive TEE examinations will be performed immediately before initiation of CPB and again after successful weaning from CPB, allowing for paired assessment of global and regional ventricular function, wall motion abnormalities, and overall myocardial performance in the immediate reperfusion period.
Secondary clinical observations will include intraoperative rhythm disturbances, need for electrical cardioversion or defibrillation, postoperative ventricular function, requirements for mechanical circulatory support, incidence of postoperative atrial fibrillation, length of intensive care unit and hospital stay, perioperative myocardial infarction, and mortality.
Safety monitoring will be conducted throughout the trial. Given the ultra-short half-life of adenosine and its extensive use in clinical cardiology, adverse effects are expected to be transient and self-limited, most commonly brief atrioventricular conduction disturbances or asystole occurring immediately after administration. These effects are anticipated to resolve spontaneously within seconds in the controlled operative setting. All adverse events will be recorded and reviewed according to predefined safety protocols.
By integrating biochemical markers, echocardiographic assessment, and clinical outcomes, this trial aims to provide a comprehensive evaluation of adenosine as an adjunct to conventional cardioplegia. The findings may help clarify its role in mitigating ischemia-reperfusion injury and inform future myocardial protection strategies in adult cardiac surgery.
Hospital Nossa Senhora da Conceicao is the lead sponsor of 21 studies on the registry; 5 are open to participants now.
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Exclusion Criteria:
Drug: Adenoseine
Drug: Placebo (sterile distilled water)
Participants randomized to the adenosine group will receive a single bolus of adenosine 1.2 mmol/L (24 mg) administered directly into the aortic root immediately after aortic cross-clamping and immediately before infusion of standard del Nido cardioplegia. The solution will be prepared by the perfusionist under sterile conditions.
Participants randomized to the placebo group will receive a single bolus of sterile distilled water, matched in volume and appearance to the adenosine solution, administered into the aortic root immediately after aortic cross-clamping and immediately prior to infusion of standard del Nido cardioplegia. The solution will be prepared by the perfusionist under sterile conditions to ensure identical volume and appearance to the placebo solution. Perioperative and postoperative management will be identical to the intervention group.
High-sensitivity troponin
Time frame: baseline (upon entry to the operating room) and at 2, 12, and 24 hours after aortic cross-clamp release
Vasoactive-Inotropic Score (VIS)
The VIS will be calculated based on the administration of vasoactive drugs using the formula described by Gaies: VIS = (dopamine µg/kg/min) + (dobutamine µg/kg/min) + (epinephrine µg/kg/min × 100) + (norepinephrine µg/kg/min × 100) + (milrinone µg/kg/min × 10) + (vasopressin units/kg/min × 10,000).
Time frame: Immediately after completion of surgery and at 12 and 24 hours after aortic cross-clamp release
TEE assessment of myocardial protection
by transesophageal echocardiography (TEE)
Time frame: The first measurement will be done at the day of the surgery in the operating room befere skin incision and the second one will be done whitin 1 hour after separation from cardiopulmonary bypass
Arrhythmias requiring cardioversion or defibrillation
Time frame: Perioperative
Need for temporary pacing
Requirement for temporary pacing due to atrioventricular block or bradyarrhythmias
Time frame: Periprocedural
New-onset atrial fibrillation
New atrial fibrillation assessed by electrocardiography
Time frame: Day 1
Use of mechanical circulatory support
The necessity of ECMO (Extracorporeal Membrane Oxygenation)
Time frame: Perioperative period (during hospitalization after surgery)
Mortality
Time frame: Perioperative period (during hospitalization after surgery)
New ischemic stroke
Confirmed by cranial computed tomography (CT) or magnetic resonance imaging (MRI)
Time frame: Perioperative period (during hospitalization after surgery)
Acute myocardial infarction
Defined according to current guidelines for post-cardiac surgery myocardial infarction (Type 5 myocardial infarction), as defined by the Fourth Universal Definition of Myocardial Infarction: a postoperative cardiac troponin elevation \>10 times the 99th percentile upper reference limit (or a \>20% rise from an elevated baseline with an absolute value \>10× the 99th percentile), in addition to at least one of the following: new pathological Q waves or left bundle branch block, angiographically documented new graft or native coronary artery occlusion, or imaging evidence of new loss of viable myocardium or new regional wall motion abnormality consistent with ischemia.
Time frame: Perioperative period (during hospitalization after surgery)
Arterial blood gas parameters
Measurement of arterial blood gas variables obtained from arterial blood samples, including: pH (unitless), PaO₂ (mmHg), PaCO₂ (mmHg), HCO₃- (mmol/L), Base excess (mmol/L)
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Complete blood count
Laboratory assessment of complete blood count obtained from arterial blood samples, including: hemoglobin \[g/dL\], hematocrit \[%\], leukocyte count \[×10⁹/L\], platelet count \[×10⁹/L\]
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Serum lactate level
Measurement of lactate concentration (mmol/L) obtained from arterial blood samples.
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
C-reactive protein
Measurement of C-reactive protein level (mg/L) obtained from arterial blood samples.
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Blood glucose
Measurement of blood glucose level (mg/dL) obtained from arterial blood samples.
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Serum electrolyte concentrations
Measurement of electrolyte concentrations obtained from arterial blood samples, including: Sodium (mmol/L), Potassium (mmol/L), Chloride (mmol/L)
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Blood lactate dehydrogenase concentration
Measurement of lactate dehydrogenase (LDH) concentration (U/L) obtained from arterial blood samples through laboratory analysis.
Time frame: On the day of surgery and at 12 and 24 hours after aortic cross-clamp release
Plan to share: No — No individual data will be used
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