Acute myocarditis, a rare and heterogeneous condition, poses significant clinical challenges due to its varied presentations, which range from mild chest pain to life-threatening cardiogenic shock (CS). Early and accurate risk assessment is critical, especially for identifying patients who may require advanced interventions like veno-arterial extracorporeal membrane oxygenation (VA-ECMO). This study aimed to address this gap by developing the Korean Acute Myocarditis (KAM) score, a predictive model for determining the likelihood of VA-ECMO implementation based on clinical and laboratory parameters.
The study retrospectively analyzed 841 patients diagnosed with acute myocarditis across seven tertiary hospitals in Korea from 2004 to 2022. Patients were either clinically suspected or biopsy-proven cases of acute myocarditis, adhering to diagnostic criteria established by the European Society of Cardiology. The dataset was split into training (621 patients) and testing (220 patients) cohorts, ensuring robust external validation of the predictive model.
The researchers identified eight key clinical predictors of VA-ECMO requirement using logistic regression analysis. These included:
- Initial mean blood pressure <65 mmHg,
- Cardiac arrest,
- Glasgow Coma Scale score ≤12,
- Platelet count <100×10³/mL,
- Pulmonary congestion on chest X-ray,
- QRS interval ≥120 ms,
- Left or right bundle branch block, and
- Left ventricular ejection fraction (LVEF) <40%.
Each variable was assigned a weight based on its β coefficient in the regression model, resulting in the development of the KAM score. This scoring system ranged from 0 to 21 points, with higher scores indicating greater risk of requiring VA-ECMO. A cutoff score of 8 was established to optimize sensitivity (90.7%) and specificity (88.7%), with an area under the curve (AUC) of 0.945 for the training cohort and 0.921 for the testing cohort.
The KAM score demonstrated excellent predictive ability for VA-ECMO use and was also associated with in-hospital mortality. Patients with higher KAM scores had a significantly elevated risk of mortality, even if VA-ECMO was not utilized. This finding underscores the tool’s value in stratifying risk and potentially guiding clinical management to improve outcomes. For instance, patients with high KAM scores could be prioritized for advanced therapies or transferred to facilities capable of delivering VA-ECMO, while low-risk patients might avoid unnecessary interventions.
The study further highlighted the real-world applicability of the KAM score. It utilizes readily available clinical and laboratory data, making it accessible for diverse healthcare settings. Additionally, the KAM score’s simplicity allows for rapid calculation, enabling timely decision-making during acute presentations of myocarditis.
Despite its strengths, the study has limitations. As a retrospective analysis, it lacked standardized protocols for VA-ECMO implementation, introducing potential variability in treatment approaches. Furthermore, while the participating centers were tertiary care facilities with expertise in managing severe myocarditis, this context may limit the generalizability of the findings to less specialized settings. External validation in broader populations is needed to confirm the model’s applicability.
Another limitation was the reliance on clinical diagnoses, which may have included patients with conditions mimicking myocarditis. However, all participants met established diagnostic criteria, and the proportion of biopsy-proven cases in this study was comparable to or exceeded that in previous research.
In conclusion, the KAM score represents a significant advancement in the management of acute myocarditis. By integrating eight simple clinical parameters, it provides a reliable tool for predicting VA-ECMO requirement and risk stratification. If widely adopted, the KAM score could facilitate early identification of high-risk patients, enabling timely interventions that improve survival rates and reduce the burden of unnecessary treatments for lower-risk individuals. Future prospective studies should focus on validating the KAM score in diverse healthcare settings and developing standardized protocols for its clinical application.
This novel scoring system has the potential to transform the care of acute myocarditis by providing clinicians with an evidence-based framework for decision-making, ultimately enhancing patient outcomes and resource utilization.
