Endomyocardial biopsy in cardiogenic Shock: experience from a contemporary CICU portuguese cohort

Abstract Background Endomyocardial biopsies (EMB) are a useful diagnostic tool in the etiological investigation of patients presenting with cardiogenic shock (CS). They assist in determining the underlying cause, such as myocarditis, cardiac allograft rejection, or other rare conditions, which can guide management and treatment strategies. Methods Retrospective analysis of CS patients admitted to a Cardiac Intensive Care Unit (CICU) from 2017 to 2024, who underwent EMB for CS etiology clarification. Data on demographics, diagnosis, procedure details and safety outcomes were analyzed. Results Out of 365 patients, 15 (4%) underwent EMB during CICU admission for CS. EMB was performed at bedside in the CICU in 60% (n=9) of cases, with the remaining performed at the catheterization laboratory. Notably, 47% of patients (n=7) were under veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support, with anticoagulation being temporarily interrupted at the time of the procedure (Figure 1 - A). Main indications were suspected acute myocarditis (40%, n=6), clarification of CS etiology (26%, n=4) and exclusion of acute cardiac allograft rejection (26%, n=4). Venous jugular access was used in 11 patients (73%), while venous femoral access and arterial radial access were used in 1 and 2 patients, respectively (Figure 1 - B). Eighty-seven percent (n=13) of samples were obtained from the right ventricle, with 5 (IQR 3-6) myocardial tissue fragments obtained per procedure. In terms of safety, there were no recorded major complications, such as ventricular tachycardia, pericardial effusion or cardiac tamponade, stroke, or pneumothorax. For patients with suspected acute myocarditis, 83% of EMB yielded a positive result; additionally, viral nucleic acid testing by RT-PCR identified Parvovirus B19 in one patient. CS etiology was only clarified in 1 patient diagnosed with AL amyloidosis; another patient had Parvovirus B19 identified, but no Dallas criteria for acute myocarditis were met. Furthermore, acute cardiac allograft rejection was confirmed in 1 of the 3 EMB performed in suspected cases (the 4th being a control EMB after treatment for acute cellular and humoral allograft rejection) (Figure 1 - C). Conclusion EMB was a safe and valuable diagnostic procedure in patients with CS, particularly in confirming acute myocarditis and excluding acute cardiac allograft rejection. The absence of major complications, even when performed at the bedside at the CICU and with ongoing VA-ECMO support underscores the procedure's safety and feasibility in this setting.