Clinical Report: Melatonin's Protective Role in Cardiac Ischemia-Reperfusion Injury

Overview

Cardiac ischemia-reperfusion injury (IRI) exacerbates myocardial damage through oxidative stress and mitochondrial dysfunction. Melatonin has demonstrated potential cardioprotective effects by preserving mitochondrial integrity and function, although clinical translation remains challenging.

Background

Cardiac IRI occurs when blood flow is restored to ischemic myocardium, paradoxically worsening cellular injury via oxidative stress and mitochondrial damage. Mitochondria are central to this process, with calcium overload and reactive oxygen species triggering mitochondrial permeability transition pore (mPTP) opening and cell death. Melatonin, an endogenous hormone, modulates mitochondrial function by scavenging reactive oxygen species, enhancing antioxidant defenses, and preserving mitochondrial structure. Despite promising preclinical data, clinical trials have yet to confirm melatonin's cardioprotective efficacy in humans.

Data Highlights

Key Findings

• Cardiac IRI worsens myocardial injury by promoting oxidative stress, calcium overload, and mPTP opening leading to cell death.
• Mitochondrial dysfunction is a key mediator in IRI pathophysiology, including disrupted ATP synthesis and membrane integrity.
• Melatonin crosses cellular membranes and exerts mitochondrial protection by scavenging ROS, enhancing antioxidant enzymes, and preserving mitochondrial structure.
• Preclinical studies show melatonin reduces infarct size and improves cardiac function after IRI.
• Translation to large animal models and clinical trials has been inconsistent, with neutral cardioprotective outcomes reported.
• Discrepancies between preclinical and clinical results highlight challenges in developing mitochondria-targeted therapies for IRI.

Clinical Implications

Melatonin shows promise as a mitochondrial-targeted agent to mitigate cardiac IRI by reducing oxidative stress and preserving mitochondrial function. However, current clinical evidence does not support routine use for cardioprotection. Further research is needed to optimize dosing, timing, and patient selection to improve translational success.

Conclusion

Melatonin offers mechanistic benefits in protecting mitochondria during cardiac IRI, but clinical efficacy remains unproven. Addressing translational challenges is essential to harness its potential in improving outcomes after myocardial ischemia-reperfusion.

References

1. Global Burden of Disease Study 2021 -- Ischemic Heart Disease Mortality
2. Meta-analysis of Melatonin in Preclinical Cardiac IRI Studies -- Cardioprotection Evidence
3. Experimental Studies on Animal Models of IRI -- Neutral Cardioprotection Outcomes
4. Clinical Trials of Melatonin in Cardiac IRI -- Neutral Results