Blunt cardiac injuries (BCIs) have a wide clinical spectrum, ranging from asymptomatic myocardial contusion to cardiac rupture and death. BCIs have been reported to occur in 20% to 76% of all patients with blunt thoracic trauma, whereas blunt cardiac rupture has been reported to occur in 0.16% to 2% of affected patients [1-6]. BCIs rarely require surgical intervention, but can be rapidly fatal. Therefore, a severe BCI may require prompt evaluation and surgical treatment [7]. In addition, it may be necessary to evaluate the prognosis to determine the surgical method before surgery [8]. Thus, the aim of this study was to identify potential factors associated with in-hospital mortality after surgery in patients with BCI and to review our experiences of the surgical management of BCI.

The study was approved by the Institutional Review Board (IRB) of the Gachon University Gil Medical Center (IRB No. GDIRB2020-392), which waived the requirement for informed consent because of the retrospective nature of the study.

The overall mortality rate after surgery was 26.6%. Non-survivors showed a significantly higher ISS (p=0.001) and AIS in the chest region (p=0.001) than survivors. AAST-OIS grade V was significantly more frequent in non-survivors than in survivors (p=0.031). Non-survivors had a significantly higher median number of units of preoperative PRBC transfusions (p=0.019) and were significantly more likely to have preoperative cardiac arrest (p=0.001) than survivors (Table 1). There was no significant difference between the two groups with respect to preoperative troponin I (p=0.392) and creatine kinase-myocardial band levels (p=0.851). However, initial pH (p=0.010), lactate (p=0.026), and base excess (BE; p=0.026) levels showed significant differences between the two groups (Table 2).

The left ventricle was the most common site of injury in non-survivors and the pericardium was the most common site of injury in survivors; however, this difference did not reach statistical significance (p=0.053). Median sternotomy was performed all survivors, but in non-survivors, left anterolateral thoracotomy and clamshell thoracotomy were performed, as well as median sternotomy (p=0.016) (Table 3). Postoperative complications, such as severe coagulopathy (n=2) or heart failure (n=1), were significant more frequent in non-survivors than in survivors (p=0.009) (Table 4).

BCIs may range from asymptomatic cardiac contusion with minor ECG abnormalities to fatal cardiac rupture [1-5]. While blunt cardiac rupture is rare, it may result in rapid hemodynamic deterioration [4,5]. Therefore, a rapid diagnostic tool is needed to detect BCI early. In addition, it is necessary to evaluate prognostic factors for BCI in the initial phase of trauma.

In our results, non-survivors had higher ISS, AIS in the chest region, and AAST-OIS grades, more preoperative PRBCs transfused, and a higher frequency of preoperative cardiac arrest. These factors reflect high-energy, severe injuries, and have been identified as poor prognostic factors in previous studies [2,8-10]. The overall mortality after surgery was 26.6%, which is similar to that of prior studies [1,11]. Cardiac tamponade was common in both groups before surgery. A previous study also reported a high incidence of cardiac tamponade after blunt cardiac rupture [12]. Cardiac tamponade secondary to BCI is extremely serious and requires rapid management.

Our data revealed that, unlike previous studies [13-16], ECG and cardiac enzymes had low diagnostic value and prognostic value in the early of BCI. Instead, pH, lactate, and BE emerged as potential prognostic factors associated with in-hospital mortality related to severe bleeding. In a previous study, increased lactate levels were identified as a strong predictor of in-hospital mortality [9]. Although we could not perform a multivariate analysis due to the small number of subjects, preoperative cardiac arrest, injury site, blood transfusion requirements, and the above blood measurements were important factors for predicting in-hospital mortality; further research is needed to validate these findings in the future.

Furthermore, non-survivors mainly had atrial and ventricular injuries, of which half were left ventricular. These results are consistent with other studies [1,8,12]. LOHS, LOICUS, MV duration, and complications were analyzed as clinical outcomes. Since most non-survivors died shortly after arrival at the emergency room, LOHS, LOICUS, and MV duration cannot be regarded as meaningful results. However, postoperative complications were significantly more common in non-survivors, and these complications were mainly severe coagulopathy and heart failure. These complications are similar to those reported in previous studies [5,7,12]. In survivors, median sternotomy was the primary approach, whereas in non-survivors, half of patients underwent left anterolateral thoracotomy or clamshell thoracotomy. This is because most of the survivors had pericardial injuries or localized injuries to the heart on preoperative imaging studies, whereas non-survivors had associated thoracic injuries or severe hemorrhage. If the patient was hemodynamically unstable or had cardiac arrest before surgery, surgeons showed a tendency to initially select resuscitative thoracotomy as a therapeutic option. This approach has also been recommended in recent guidelines [17,18].

This study has some limitations. First, this was a retrospective, single-center study. Second, the small sample size limits the ability to generalize the findings. Third, a multivariate analysis could not be performed to identify predictors of in-hospital mortality because of the small number of subjects. Thus, we are planning a multicenter study to overcome these limitations.

In conclusion, we found that initial pH, lactate, BE, ventricular injury, the amount of preoperative PRBC transfusions, and preoperative cardiac arrest may be predictors of in-hospital mortality. If patients with BCI before surgery have these factors, surgeons should consider expeditious salvage interventions, including cardiopulmonary bypass or damage control surgery.