The Impact of Re-Opening Post Cardiac Surgery on Short and Long- Term Outcomes: 11 Years Follow Up

  

    
Variable
    
P value
    
Hazard ratio
  
  

    
Reopening
    
0.001
    
3.19
  
  

    
Multisystem failure
    
0.001
    
20.01
  
  

    
Post op MI
    
0.001
    
7.16
  
  

    
Post op wound infection
    
0.001
    
0.07
  
  

    
Bypass time
    
0.001
    
1.01
  
  

    
Xclamp time
    
0.001
    
0.98
  

Table 8: Predictors of in hospital mortality.

Discussion

Re-exploration after cardiac surgery has been considered as an adverse event that affects the patient’s morbidity and mortality. However, patients who need re-exploration, especially after postoperative haemorrhage, may not necessarily have a poor outcome. While it is true that various factors associated with re-exploration have been found to individually affect the patient’s outcome rather than the re-exploration itself, we present a study comparing two groups after a careful propensity match score to elucidate the implications related to the re-opening itself after haemorrhage and tamponade.

Data varies across the globe in different cardiac surgery centers. Incidence of urgent resternotomy for bleeding after cardiac operation has been reported to be 2-6%. Smarason et al. [10] showed an 8% reoperation rate for bleeding, which was higher compared to other studies. In our study we found the overall re-exploration rate to be 6.8% which was comparable to most of the studies.

In terms of differentiating morbidity and mortality, we found different results depending on the studies observed. Kathik et al. [1] demonstrated worse outcomes in terms of morbidity after surgical exploration (low cardiac output, renal failure, prolonged mechanical ventilation and ICU/hospital stay) but not significantly higher mortality rate. Conversely, Moulton et al. [6] found a significantly higher mortality rate in addition to an increased risk of sepsis, renal failure, and prolonged ventilation. There was the need of conducting large population studies, and Ranucci and co-workers [11] analyzed a large population in a retrospective manner, finding the following: Firstly, the mortality is double than expected in patients requiring surgical exploration because of post-operative bleeding. Secondly, the number of units of blood transfused is an independent risk factor for morbidity (low cardiac output, acute renal failure, sepsis) and mortality. Thirdly, the timing of the re exploration is not associated with increased morbidity or mortality. However, the latter statement was refused by Chong and co-workers [2] demonstrating that reexploration after 12 hours from the end of the procedure has a higher need or intra-aortic balloon pump support, longer ICU stay, and increased mortality.

In our study, we focused on the two main causes of re-exploration, which are post-operative haemorrhage and cardiac tamponade. A Japanese study by Kubota and co-workers [12] showed that when re-exploration due to bleeding was required, the mortality increased significantly over non-haemorrhagic indications for re-opening. Moreover, it showed there was not significant difference in the interval time between the operation and death according to whether re-exploration for bleeding had been performed. Our study is one of the few that performed a propensity matched score between patients re-opened for bleeding, meaning that the only difference among the two groups is whether or not a re-exploration was performed, and our results should be attributed to the events following a reopening.

We acknowledge the work of Ranucci and Vivacqua [11,13] on demonstrating independent association between greater transfusion and reoperation with major mortality and morbidity, but this was not included in our study as cases followed expert consensus transfusion strategies. All our re-explorations were carried out either in the ICU or theatre, and the results correlate well with other international studies. In our study, place of re- exploration is not a factor affecting outcome.

In our series, the incidence of re-exploration, its complications and outcome was independent to the age and sex of the patient. The propensity score matching of the baseline demographics revealed comparability among the two groups without any outstanding differences.

Preoperatively, multivariate analysis identified poor LV, preoperative use of IABP and post op arrhythmias as significant (p<0.001) determinants of reopening.

Patients with pre op intra-aortic balloon pump (IABP) and intravenous inotropes were most re explored (p=0.846 and p=0.005), respectively, among groups. We could identify IABP as a predictor of re-opening by itself (p=0.001, HR 2.243). We suspect that in a larger series this significance would have an impact in the outcome of the patient, although in our study the level of support to the heart required prior to the re-opening did not necessarily affect the final outcome of the patient.

Dacey et al. [9] showed in their study association of prolonged CPB time with increased incidence of re exploration. In our study, the groups are matched by cross-clamp and bypass time (p=0.258 and p=0.323, respectively), hence the difference is not significant. However, there were statistically higher rates of post-operative morbidities including Major Adverse Cerebrovascular and Cardiovascular events (MACCE) and renal failure in the re-explored group compared to the control group (p<0.0001).

Fröjd and co-workers [14] recorded up to a twofold increased early postoperative mortality rate. The mortality rate in our study in re-explored patients at 30 days was higher in the reopened group versus the control group (23.4% vs. 6.3%). Brown et al. [15] described in a recent cohort a worse long-term survival in those who had cardiac re exploration, however a Kaplan-Meier survival estimation and multivariable Cox regression analysis were performed to assess the impact of re-exploration on survival.

So, as per the results of this study, the long-term survival (up to 11 years follow up) was isolated and it showed 63.0% in the reopened group compared to 77.1% in control group (Log Rank <0.0001). Interestingly, patients who were discharged alive, had a comparable long-term survival 82.4% versus 84.9% in Reopened and control groups respectively (Log Rank = 0.396).

Conclusion

Reopening for bleeding and/or Tamponade saves lives. However, in this propensity matched study we have shown that reopening is also associated with a significantly higher rate of post-operative complications; hospital stay, short- and long-term mortality compared to similar risk profile patients who were not reopened. Re opening post cardiac operation is an independent predictor of in hospital mortality. Meticulous haemostasis is required to reduce risk of bleeding/tamponade and prevent re opening post cardiac surgery.

References

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