When does pericardial fluid analysis add diagnostic value? Tumor-specific cytological yield and clinical burden in Oncology Patients

Background In oncology patients, pericardial effusion (PE) frequently prompts invasive investigation, yet the diagnostic yield of pericardial fluid analysis and its relationship with clinical burden remain incompletely defined in contemporary cardio-oncology practice. Methods We retrospectively reviewed all consecutive oncology patients diagnosed with PE between January 2019 and December 2024 at a tertiary cardio-oncology center. Demographic characteristics, cardiovascular comorbidities, oncologic diagnosis, clinical presentation, echocardiographic severity, and pericardial fluid findings were collected. The primary aim was to describe the diagnostic yield of pericardial fluid analysis across tumor types. Secondary aims included characterization of clinical burden, defined by symptom severity, echocardiographic impact, and need for invasive management. Results Eighty patients were included. Mean age at PE diagnosis was 67 ± 13 years, with 62% aged ≥65 years, and 58% were male. Cardiovascular comorbidities were highly prevalent, including arterial hypertension (56%), dyslipidemia (41%), diabetes mellitus (29%), chronic kidney disease (27%), coronary artery disease (22%), and pre-existing heart failure (24%). Primary malignancies included lung cancer (32%), breast cancer (18%), hematologic malignancies (15%), gastrointestinal tumors (14%), urologic cancers (9%), mediastinal tumors (7%), and other malignancies (5%). At PE diagnosis, 64% of patients had metastatic disease and 45% were receiving palliative oncologic treatment. Dyspnea was the most common presenting symptom (48%), while 21% of PE were detected incidentally. Echocardiography revealed large effusions in 46%, with signs of tamponade in 18%. Pericardial fluid analysis was performed in 81% of patients. Overall, malignant cytology was identified in 44%, with significant variation by tumor type (p=0.008): lung cancer (63%), hematologic malignancies (58%), breast cancer (31%), and gastrointestinal tumors (18%). Cytology-positive effusions were more frequently large (61% vs 34%, p=0.02) and required invasive management (86% vs 59%, p=0.01). Conclusions In this contemporary cardio-oncology cohort, pericardial effusion was associated with substantial clinical burden and frequently required invasive evaluation. The diagnostic yield of pericardial fluid analysis varied markedly according to tumor type and correlated with echocardiographic severity. These findings support a tailored, tumor-aware approach to the diagnostic work-up of pericardial effusion in oncology patients.