Various scoring systems have been employed to predict postoperative mortality and morbidity in patients with liver cirrhosis. These include CP score, Model for End-stage Liver Disease (MELD) score, Society of Thoracic Surgeons (STS) score, European System for Cardiac Operative Risk Evaluation (EuroSCORE), and Simplified Acute Physiology Score (SAPS) III. The CP Classification was initially developed empirically for patients with bleeding esophageal varices. It uses the albumin, prothrombin time, serum bilirubin, degree of ascites, and presence of encephalopathy to characterize the severity of liver cirrhosis. It has been found to be a reliable predictor of functional status of liver and overall survival [7]. It correlates strongly with postoperative mortality and morbidity in the patients who underwent cardiac surgery [2–5, 7, 8]. MELD score was developed in 2000 to stratify survival of patients after transjugular intrahepatic portosystemic shunt (TIPS) procedure. It is validated for predicting survival of patients with end-stage liver disease [4, 7, 9].

Filsoufi et al. did not find MELD scores to be significantly associated with hospital mortality [3], while the CP classification and its associated numerical score appropriately predicted mortality and morbidity [1–4, 7, 10]. Their study confirmed the predicted value of CP Classification; albeit, the sample size was small. On the other hand, Thielmann et al. found the MELD score to be the most predictive risk evaluation model with clear superiority to CP Classification and EuroSCORE. The best value for MELD score was found to be 13.5 with a sensitivity of 52% and specificity of 79%. CP Classification was found to be useful as well. The hospital and long term outcomes were better with CP Class A as compared to Classes B and C. Class C fared the worst [9].

CP Classification remains the best means for predicting mortality after cardiac surgery [3]. In the current literature, CP Classification is used most commonly. The numerical score associated with CP Classification is considered particularly helpful in stratifying the risk for cardiac surgery with CPB in patients with liver cirrhosis [4, 7].

Cirrhosis is not considered a risk factor in the STS score and EuroSCORE. EuroSCORE was not particularly useful in predicting the risk in patients with cirrhosis requiring cardiac surgery [9, 11]. However, a recent German study demonstrated a significant predictive power of EuroSCORE for 30 day mortality [12]. Simplified Acute Physiology Score (SAPS) III has been noted to have the best predictive value for long term outcomes [10].

If carefully examined, most of these risk scores rely on the synthetic function of the liver measured by serum bilirubin, prothrombin time, and international normalized ratio (INR); the stigmata of advanced liver disease like presence of ascites and encephalopathy; and the markers of end organ dysfunction like serum creatinine. Any patient with a high CP or MELD score reflects the advanced liver dysfunction with the derangements of coagulation, renal function, and portal hypertension associated with ascites and splenomegaly. Blood tests to estimate hepatic functional reserve, like indocyanine green clearance and asialoscintigraphy may augment the evaluation of hepatic function; but, their use as a preoperative risk evaluation tool has not been well characterized [13, 14].

Thrombocytopenia associated with splenomegaly is also considered to be a significant predictor of risk in patients with cirrhosis undergoing cardiac surgery. Filsoufi et al. reported a statistically significant in-hospital mortality associated with a low preoperative platelet count [3]. Thielmann et al. similarly noted that preoperative thrombocytopenia is adversely associated with survival after cardiac surgery in patients with cirrhosis [3, 9].

A Cleveland Clinic study by Suman et al. further delineated the correlation of a higher CP and MELD scores to hepatic decompensation after cardiac surgery with CPB. For patients with a CP score >7, there is an association of hepatic decompensation and mortality with a 86% sensitivity and 92% specificity for predicting mortality in addition to a 66% sensitivity and 97% specificity for predicting hepatic decompensation. MELD score with a value of >13 offered a 71% sensitivity and 89% specificity for mortality. Hepatic decompensation under the receiver operative curve (ROC) for mortality was similar for both scores. The best values for predicting mortality and hepatic decompensation were determined to be >7 for CP and >13 for MELD score. These findings confirm the poor prognosis noted in patients with CP Classes B and C in other studies [7]. The individual parameters of serum bilirubin, albumin, and INR were not strongly associated with mortality. This Cleveland Clinic study concluded that the risk for postoperative mortality in patients with cirrhosis considered for cardiac surgery with CPB was assessed accurately by using the numerical CP score and a score >7 was associated with higher mortality [7].

The risk of complications is high in all CP Classes; but, some studies report a comparable or acceptable risk in propensity matched population in patients with a CP score <8 [4]. Klemperer et al. noted that 100% of patients with CP Class B and 25% of those with CP Class A had major complications [1]. Arif et al. noted longer intensive care unit stay, longer duration of invasive ventilation, tracheostomy, and demand for red blood cells, plasma, and platelets in patients with cirrhosis who did not survive 30 days after cardiac surgery [12]. In this group, renal failure, neurological complications, sepsis, and gastrointestinal complications were higher. The patients with liver cirrhosis stayed twice as long in the hospital as compared to their matched controls. Prolonged hospital stay was primarily due to hepatic decompensation and renal failure rather than the need for mechanical ventilation and pressor support requiring [4]. Length of stay was substantially higher for patients with cirrhosis versus those without cirrhosis (9 vs. 6 days). Similarly, patients with cirrhosis accrued up to 34% higher hospital charges [5].

Common postoperative complications include coagulopathy and thrombocytopenia, resulting in increased postoperative bleeding. An early complication after CPB is a lack of vascular tone. It is unclear why this happens; but, most of the patients with cirrhosis show very low systemic vascular resistance (SVR) requiring high-dose vasoactive agents to maintain systemic blood pressure.

A number of studies demonstrated the high risk associated with open heart surgery in patients with liver cirrhosis [1–12]. Overall in-hospital mortality is high among patients with liver cirrhosis. Various single institution studies have reported 17–31% in-hospital mortality (Arif et al.: 30-day mortality 26% [12]; Shaheen et al.: 17.2% [5]; Filsoufi et al.: 26% [3]; Klemperer et al.: 31% [1]). Most of these studies had a small number of patients precluding definitive conclusions being drawn. Definitive conclusions could not be drawn from these studies due to small sample sizes. However, one common theme emerges that CP Classes B and C have a very high risk of mortality and morbidity. Patients with CP Class C have up to a 100% mortality associated with open heart surgery [1–12]. Mortality rates of 0–20%, 18–50%, and 67–100% have been reported in patients with CP Classes A, B, and C, respectively [1–12].

The overall 5-year survival rate is noted to be 19% for all CP Classes. Patients with CP Class C had a 0% 5-year survival, while patients with CP Class A had a 25% 5-year survival. In Arif et al.’s study, 1-year and 5-year survival rates of CP Class A patients were 70% and 26%, CP Class B patients 33% and 5%, and CP Class C patients 33% and 0%, respectively, suggesting a somewhat prohibitively high risk for elective cardiac surgery in CP Class C patients [12]. Another study shows excellent long-term survival for all CP Classes of 78.6% at 3 years and 70.2% at 5 years [8]. Their findings suggest that the survival after 3 years becomes similar to the survival in the general population undergoing cardiac surgery. In another study, long-term survival was 82.4% for CP Class A, 47.6% for CP Class B, and 33.3% for CP Class C patients [10].