Baseline clinical characteristics
The baseline characteristics of the 97 subjects are shown in Table 1; the majority were male and > 65 years of age. Approximately 10% of the patients had previously taken antiplatelet agents, but few patients had received prior anticoagulation therapy. The most frequent etiology in patients undergoing pericardiocentesis was malignant disease (58.8%), and among these patients, 59.6% had lung cancer (Table 2). Pericardial fluid with malignant cells: positive-cytology was demonstrated in 76.8% of the patients in the malignancy group.
Table 1
The patients’ baseline characteristics
Characteristic | n = 97 |
Age (years) | 66.1 ± 14.2 |
Men (%) | 58 (59.8) |
Medications (%) | |
Prior antiplatelet | 10 (10.3) |
Prior novel oral anticoagulants | 6 (6.2) |
Prior warfarin | 5 (5.2) |
Symptom (%) | |
Dyspnea | 84 (86.6) |
Cough | 15 (15.5) |
Anorexia | 10 (10.3) |
Chest pain | 9 (9.3) |
Syncope | 5 (5.2) |
Primary drained pericardial effusion (ml) | 550.87 ± 262.31 |
Etiology (%) | |
Malignancy | 57 (58.8) |
Collagen vascular diseases | 8 (8.2) |
Idiopathic | 7 (7.2) |
Infection | 5 (5.1) |
Post-myocardial infarction | 4 (4.1) |
Uremia | 4 (4.1) |
Iatrogenic | 3 (3.1) |
Post-surgery | 3 (3.1) |
Chronic graft-versus-host disease | 3 (3.1) |
Radiation | 1 (1.0) |
Dissection | 1 (1.0) |
Hypothyroidism | 1 (1.0) |
The baseline clinical characteristics of all subjects are shown. |
Table 2
Etiologies in the malignancy group
Malignancy | n = 57 |
Lung cancer | 34 (59.6) |
Gastrointestinal carcinoma | 7 (12.3) |
Malignant lymphoma | 3 (5.3) |
Renal carcinoma | 3 (5.3) |
Breast carcinoma | 2 (3.5) |
Gynecological carcinoma | 2 (3.5) |
Pleural mesothelioma | 1 (1.8) |
Hemangiosarcoma | 1 (1.8) |
Primary cancer of unknown type | 4 (7.0) |
Among patients with malignant disease, patients with lung cancer constituted the highest percentage. |
Blood samples (Table 3)
No significant differences in serum C-reactive protein (CRP), total protein, LDH, albumin, glucose, and Hb were observed between the malignancy and non-malignancy groups. In contrast, estimated glomerular filtration rate (eGFR) was significantly higher in patients with vs without malignancy (60.56 ± 31.42 ml/min/1.73m2 vs 45.97 ± 29.08 ml/min/1.73m2, respectively; p = 0.024). Serum brain natriuretic peptide (BNP) levels were significantly lower in patients with vs without malignancy (126.89 ± 183.35 pg/ml vs 409.18 ± 868.67 pg/ml, respectively; p = 0.037).
Table 3
Comparison between the malignancy and non-malignancy groups
Serum component | Malignancy Group | Non-Malignancy Group | p |
CRP (mg/dl) | 5.33 ± 4.37 | 4.54 ± 6.70 | 0.488 |
eGFR (ml/min/1.73m2) | 60.56 ± 31.42 | 45.97 ± 29.08 | 0.024 |
Total protein (g/dl) | 6.08 ± 0.60 | 6.06 ± 1.27 | 0.889 |
LDH (U/L) | 543.35 ± 767.60 | 357.98 ± 186.54 | 0.138 |
Albumin (g/dl) | 3.01 ± 0.46 | 3.11 ± 0.75 | 0.399 |
Glucose (mg/dl) | 142.20 ± 61.03 | 134.10 ± 53.05 | 0.518 |
Hemoglobin (g/dl) | 11.01 ± 1.77 | 11.11 ± 1.60 | 0.766 |
Hematocrit (%) | 33.29 ± 5.61 | 34.24 ± 4.84 | 0.391 |
BNP (pg/ml) | 126.89 ± 183.35 | 409.18 ± 868.67 | 0.037 |
Pericardial fluid component | | | |
Ph | 7.39 ± 0.20 | 7.48 ± 0.12 | 0.069 |
Total protein (g/dl) | 5.02 ± 0.80 | 4.72 ± 1.19 | 0.166 |
LDH (U/L) | 2032.10 ± 3522.33 | 1029.58 ± 1561.52 | 0.106 |
Albumin (g/dl) | 2.66 ± 0.53 | 2.61 ± 0.70 | 0.661 |
Glucose (mg/dl) | 78.24 ± 48.29 | 98.41 ± 44.85 | 0.048 |
ADA (U/L) | 37.59 ± 47.26 | 29.34 ± 37.66 | 0.389 |
Hyaluronic acid (ng/ml) | 31975.9 ± 27282.7 | 27194.6 ± 28745.9 | 0.438 |
Hemoglobin (g/dl) | 3.83 ± 2.22 | 5.15 ± 5.19 | 0.422 |
Hematocrit (%) | 14.79 ± 6.73 | 16.74 ± 21.36 | 0.788 |
Variable | | | |
Pericardial fluid/Serum ratio | | | |
Total protein ratio | 0.83 ± 0.14 | 0.78 ± 0.15 | 0.127 |
LDH ratio | 5.23 ± 7.69 | 2.59 ± 2.71 | 0.047 |
Glucose ratio | 0.57 ± 0.34 | 0.83 ± 0.45 | 0.005 |
Pericardial fluid/Serum total protein ratio > 0.5 | 49 (100%) | 38 (97.4%) | 0.260 |
Pericardial fluid/Serum LDH ratio > 0.6 | 47 (94.0%) | 29 (76.3%) | 0.017 |
Pericardial fluid LDH > 2/3 UNL | 49 (98.0%) | 32 (86.5%) | 0.036 |
Cytology, positive | 43 (76.8%) | - | - |
Lower serum BNP and lower pericardial fluid glucose level were associated with malignancy. |
Values are expressed as mean ± standard deviation |
CRP C-reactive protein, eGFR estimated glomerular filtration rate, LDH lactate dehydrogenase, BNP brain natriuretic protein, ADA adenosine deaminase, UNL upper limit of normal |
|
Pericardial fluid samples, pericardial/serum ratio, Light’s criteria, and cytology (Table 3).
No significant differences in pericardial fluid pH levels, total protein, LDH, albumin, ADA, and hyaluronic acid were observed between the two groups. Pericardial fluid glucose levels were significantly lower in patients with vs without malignancy (78.24 ± 48.29 vs 98.41 ± 44.85, respectively; p = 0.048) (Fig. 2).
Malignant cells in the pericardial fluid was demonstrated in 76.8% of the patients in the malignancy group. All patients were diagnosed as having exudative PE by Light’s criteria. Of the three items in Light’s criteria, LDH ratio > 0.6 and pericardial LDH > 2/3 of the UNL were associated with malignancy (p = 0.017 and p = 0.036, respectively). The pericardial fluid-to-serum LDH ratios were significantly higher in patients with malignancy than in those without malignancy (5.23 ± 7.69 vs 2.59 ± 2.71, respectively; p = 0.047). The pericardial fluid-to-serum glucose ratios were significantly lower in patients with vs without malignancy (0.57 ± 0.34 vs 0.83 ± 0.45, respectively; p = 0.005) (Fig. 2).
CT measurements
No significant differences in CT parameters were observed between the malignancy and non-malignancy groups. However, CT attenuation values (HU) tended to be higher in the malignancy group compared with the non-malignancy group (22.7 [interquartile range (IQR), 17.4–26.0] vs 17.4 [IQR, 13.7–26.4], respectively; p = 0.08).
The relationship between pericardial fluid samples and CT measurements
The malignancy group had a higher median CT attenuation value of 20.6 HU (p < 0.05). Moreover, overall, CT attenuation values > 20 HU were associated with malignancy (p < 0.05) (Fig. 3). The relationship between pericardial fluid measurements and CT attenuation values is shown in Fig. 4. CT attenuation values were strongly correlated with pericardial fluid hematocrit (r = 0.908). CT attenuation values were also correlated with pericardial fluid glucose level (r = − 0.425), protein level (r = 0.541), glucose ratio (r = − 0.461), and protein ratio (r = 0.583). Pericardial fluid glucose ≤ 70 mg/dl and CT attenuation values > 20 HU were cutoff values associated with malignancy (Fig. 5). Additionally, pericardial fluid glucose ≤ 70 mg/dl and CT attenuation values > 20 HU were also cutoff values associated with positive-cytology patients (see Supplementary Fig. 1, Additional File 1).