Among the 212 patients with complete data, 55 (25.9%) developed low cardiac output within postoperatives day 1 (quartiles 1 and 2). The baseline characteristics and comorbidities were similar between the patients with and without low cardiac output (Table 1).

The following analysis was based on the 212 complete data points unless otherwise stated. Preoperatively, 22 (10.4%) patients had atrial arrhythmia, and 21 (9.4%) cases were considered to be due to constrictive pericarditis-induced high atrial pressure. Thirty-two (15.1%) patients had renal dysfunction, and 26 (12.3%) cases were considered to be due to constrictive pericarditis-induced prerenal insufficiency. The overall rates of hypoalbuminemia, moderate to severe hyponatremia, hyperbilirubinemia, and pericardial calcification were 49.1%, 10.4%, 81.6%, and 21.7%, respectively. The mean central venous pressure was 18 ± 5 cmH2O, and the cardiac index was 1.87 ± 0.45 L•min−1•m−2.

For the between-group comparison, postoperative low cardiac output patients had higher rates of atrial arrhythmia (OR 3.32, 95%CI 1.35–8.17, P = 0.007), renal dysfunction (OR 4.24, 95%CI 1.94–9.25, P < 0.001), moderate to severe hyponatremia (OR 6.36, 95%CI 2.50–16.20, P < 0.001), and hypoalbuminemia (OR 1.99, 95%CI 1.06–3.73, P = 0.031) than patients without postoperative low cardiac output (Table 2). For echocardiography, the E peak velocity variation was greater for patients with postoperative low cardiac output than for those without (difference 2.8%, 95%CI 0.7–5.0%, P = 0.011). Other parameters, including LVEF, tricuspid regurgitation flow rate, TAPSE, diameter of the inferior vena cava, and E/A ratio, were similar between the two groups (all P >0.05). For hemodynamic parameters, postoperative low cardiac output patients had higher preoperative central venous pressure (difference 3 cmH2O, 95%CI 2–5 cmH2O, P < 0.001) and lower preoperative cardiac index (difference − 0.27 L•min−1•m−2, 95%CI − 0.41 to − 0.14 L•min−1•m−2, P < 0.001) than patients without postoperative low cardiac output (Table 2).

The multivariable logistic regression test results showed that the preoperative factors associated with postoperative low cardiac output included atrial arrhythmia (B 1.40, OR 4.04, 95%CI 1.36–12.01, P = 0.012), renal dysfunction (B 0.97, OR 2.64, 95%CI 1.07–6.50, P = 0.035), moderate to severe hyponatremia (B 1.25, OR 3.49, 95%CI 1.19–10.24, P = 0.023), high central venous pressure (B 0.15, OR 1.17, 95%CI 1.08–1.27, P < 0.001), and low cardiac index (B − 1.03, OR 0.36, 95%CI 0.14–0.92, P = 0.032), and the results showed good model fitness (Hosmer-Lemeshow test P = 0.502) and an area under the curve value of 0.79 (95% CI 0.72–0.86, P< 0.001) (Table 4 and Figs. 1 and 2).

Factors associated with low cardiac output after pericardiectomy

Receiver-operating-curve of the model predicting low cardiac output after pericardiectomy

Postoperatively, low cardiac output patients had higher rates of complications, including tachyarrhythmia (OR 8.01, 95%CI 3.89–16.48, P < 0.001), acute kidney injury (OR 6.91, 95%CI 3.41–14.02, P < 0.001), new-onset chronic renal dysfunction (OR 22.12, 95%CI 2.66–184.15, P < 0.001), and delirium (OR 14.38, 95%CI 5.38–38.46, P < 0.001); additionally, these patients used more circulatory support devices, including hemofiltration (OR 25.33, 95%CI 8.98–71.46, P < 0.001), IABP (OR 25.80, 95%CI 3.15–211.37, P < 0.001), and ECMO (OR 22.12, 95%CI 2.66–184.15, P < 0.001), and they had poorer outcomes, including longer ventilator hours (difference 104 h, 95%CI 69–135 h, P < 0.001), lengths of ICU (difference 7 days, 95%CI 5–10 days, P < 0.001), and hospital (difference 13 days, 95%CI 8–18 days, P < 0.001) stays, and higher mortality (OR 33.62, 95%CI 4.19–269.43, P < 0.001) (Table 3).

Among the 235 patients, eleven (4.7%) died perioperatively. Nine of them died in the hospital due to intractable low cardiac output. Two patients abandoned treatment and were discharged from the ICU for non-medical reasons. One of them died of multiple organ dysfunction within hours, and the other died of an unknown cause within days.

A total of 212 patients were analysed to identify independent factors associated with length of hospital stay. Preoperative renal dysfunction (B − 0.68, HR 0.51, 95%CI 0.33–0.77, P = 0.002), hyperbilirubinemia (B − 0.42, HR 0.66, 95%CI 0.46–0.94, P = 0.022), and postoperative low cardiac output (B −0.88, HR 0.42, 95%CI 0.29–0.59, P < 0.001) were associated with the length of hospital stay (Table 5 and Fig. 3).

Independent factors associated with length of hospital stay