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Long-Term Outcome and Prognostic Factors of Mortality in Patients With Surgical Pulmonary Embolectomy
*Corresponding author: Dr. Thara Tunthanathip, Department of Surgery, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand. tsus4@hotmail.com
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Received: ,
Accepted: ,
How to cite this article: Soontrapornchai S, Chittithavorn V, Tunthanathip T. Long-Term Outcome and Prognostic Factors of Mortality in Patients With Surgical Pulmonary Embolectomy. J Health Allied Sci NU. doi: 10.25259/JHS-2024-9-21-(1582)
Abstract
Objectives
Acute pulmonary embolism (PE) is a significant cardiovascular risk and one of the causes of disability and death among hospitalised patients. Surgical pulmonary embolectomy should be considered for patients with high-risk PE when thrombolysis is contraindicated or has failed. The objective of the present study was to evaluate the long-term outcome and identify the factors that are associated with the prognosis of surgical embolectomy for acute PE in response to this knowledge gap.
Material and Methods
A retrospective cohort analysis of 59 patients with acute PE who underwent pulmonary embolectomy was conducted using survival analysis. In the present study, the average follow-up duration was 1083.2 ± 1341.1 days, and the mortality rate was 15.3%. The Cox proportional hazard regression model was used to explore prognostic factors. Therefore, Kaplan-Meier survival curves were created, and log-rank tests were used to assess prognostic factors.
Results
For the total cohort, 7-day, 14-day, 30-day, and 90-day survival probabilities were 91.5% (95% confidence interval (CI) 84.7-98.9), 89.7% (95% CI 82.3-97.9), 86.1% (95% CI 77.5-95.5), and 86.1% (95% CI 77.5-95.5), respectively. Using multivariable analysis of Cox hazard regression, preoperative mechanical circulatory support (Hazard ratio (HR) 6.03, 95% CI 1.05-34.63) and postoperative major adverse cardiac events (HR 26.98, 95%CI 5.36-135.91) were associated with mortality.
Conclusion
The preoperative mechanical circulatory support and postoperative major adverse cardiac events were independent prognostic factors for PE patients who underwent pulmonary embolectomy. The predictive performances of these prognostic factors should be validated in the future.
Keywords
Prognosis
Prognostic factor
Pulmonary embolectomy
Pulmonary embolism
INTRODUCTION
Acute pulmonary embolism (PE) is an important cardiopulmonary hazard and one of the most important causes of disability and mortality among hospitalised patients.[1,2] While previous research found that the prevalence of acute PE in hospitalised patients was between 0.23-1.0%,[1,2] autopsy results revealed that the fatal complication was the cause of death in 10.4-14.6% of cases.[3,4] PE was found incidentally in 62.7% of autopsies conducted on hospitalised patients.[3]
Surgical pulmonary embolectomy is suggested for individuals with high-risk PE when thrombolysis is contraindicated (previous or current stroke, recent major surgery, or gastrointestinal bleeding) or has proven ineffective.[5,6] The postoperative mortality has been documented in a literature review, ranging from 8-25%.[7-10] Argyriou et al. studied the surgical outcomes of acute PE patients who underwent pulmonary embolectomy in the United Kingdom and reported in-hospital mortality of 25%,[7] whereas Kadner et al. reported a 30-day mortality rate following operation of 8% in Switzerland.[8] In addition, Kon et al. conducted a study in North America and reported an operational mortality rate of 16%.[9] However, very few studies have been performed on the long-term prognosis of surgical pulmonary embolectomy. Pasrija et al. used survival analysis in their study and found that the 1-year survival rate of PE patients after surgical pulmonary embolectomy was 91%, while Dohle et al. reported that the 10-year survival rate of surgical treatment of acute PE was 66.4%.[10,11]
Prognostic factors for PE patients following surgical pulmonary embolectomy have been documented as follows: age, body surface area, obesity, cardiogenic shock, unresponsive neurologic state, chronic lung disease, race, deep vein thrombosis, preoperative arrest, preoperative cardiopulmonary resuscitation, inspired oxygen fraction, venoarterial extracorporeal membrane oxygenation, payment type, and type of hospital. However, the long-term prognosis of patients after pulmonary embolectomy is still limited.[7,10,12]
The objective of the present study was to evaluate the long-term outcome and identify the factors that are associated with the prognosis of surgical embolectomy for acute PE in response to this knowledge gap.
MATERIAL AND METHODS
Study design and study population
The present study was a retrospective cohort study of patients who underwent surgical pulmonary embolectomy between January 2012 and December 2022. Patients aged <18 years, those with incomplete medical data, or who could not identify their current state, were excluded. Baseline clinical characteristics, preoperative computer tomography pulmonary angiography, preoperative laboratories, and operative data were gathered, such as age, sex, comorbidity, smoking, Troponin-T, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), lactate, simplified PE severity index (sPESI), postoperative complications, and aortic cross-clamp time.
The operational definition was created before the review of the medical records. Massive PE was defined as patients with PE who had systemic hypotension (systolic arterial pressure <90 mm) or shock, characterised by tissue hypoperfusion and hypoxia. The sPESI score was calculated from the patient’s vital signs along with patient variables such as age, sex, and comorbidities.[10] Moreover, sub-massive PE was defined as PE patients who showed right ventricular dysfunction but had no systemic hypotension or clinical shock.[10,13]
Postoperative complication of the present study was defined as postoperative adverse events after pulmonary embolectomy, including acute myocardial infarction, congestive heart failure, new-onset cardiac arrhythmias, ischemic stroke, and haemorrhagic stroke.[14]
For outcome evaluation, the starting date was defined as the date of PE diagnosis by CT pulmonary angiogram, and the follow-up data were obtained until September 2024, which included status information (death or staying alive). Follow-up data were gathered during patients’ visits to outpatient clinics or through information obtained from the death records by the local municipality.
Statistical analysis
Descriptive statistics were used to identify clinical features and imaging outcomes. For continuous variables, the mean and standard deviation were used, whereas percentages were used for categorical data. For survival analysis, the median overall survival time was assessed. The Cox proportional hazard regression model was used to investigate prognosis in both univariate and multivariable analyses. Candidate variables with a p ≤0.1 in the univariate analysis were explored in a multivariable model using backward stepwise selection to complete the final model.[15] The model with the lowest Akaike information criterion (AIC) value was chosen as the final model.
Hence, a Kaplan-Meier survival curve was established, and log-rank tests were employed to assess each predictor in the final model. Statistical analyses were performed by the Jamovi version 2.3.28 software (The Jamovi project, Sydney, Australia).
Ethical considerations
The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). A human research ethics committee of the faculty of medicine, Prince of Songkla University, approved the present study (REC.67-203-10-4). Because the present study was a retrospective cohort research, informed consent from patients was not required. However, the patient’s identification numbers were encoded before the analysis.
RESULTS
Characteristics of patients in the present cohort
The baseline clinical characteristics of the 59 individuals with acute PE have been shown in Table 1. The majority of patients were female, with an average age of 54.7 ± 15.2 years. Common comorbidities were hypertension, diabetes mellitus, and cerebrovascular disease. Furthermore, 11.9% of patients who smoke, compared to 67.8% patients who do not smoke. The majority of PE was a massive subtype, with 35.6% of patients receiving systemic heparinisation before pulmonary embolectomy.
| Factor | n (%) |
|---|---|
| Sex | |
| Male | 22 (37.3) |
| Female | 37 (62.7) |
| Mean age (SD) - year | 54.7 (15.2) |
| Body mass index -kg/m2 | 25.38 (4.06) |
| Comorbidity | |
| Diabetes mellitus | 13 (22.0) |
| Hypertension | 21 (35.6) |
| Chronic kidney disease | 3 (5.1) |
| Cerebrovascular disease | 7 (11.9) |
| Smoking | |
| Never | 40 (67.8) |
| Active | 7 (11.9) |
| Ex-smoker | 12 (20.3) |
| Right ventricular dysfunction | 30 (50.8) |
| sPESI score | |
| 0 | 6 (10.2) |
| 1 | 4 (6.8) |
| 2 | 16 (27.1) |
| 3 | 22 (37.3) |
| 4 | 11 (18.6) |
| Previous thromboembolism | 19 (32.2) |
| Severity of PE | |
| Sub-massive PE | 4 (6.8) |
| Massive PE | 55 (93.2) |
| Preoperative haemodynamic instability | 40 (67.8) |
| Preoperative cardiac arrest | 29 (47.5) |
| Previous systemic thrombolysis | 2 (3.4) |
| Previous systemic heparinisation | 21 (35.6) |
| Previous catheter-directed thrombectomy | 1 (1.7) |
| Preoperative mechanical ventilation support | 36 (61.0) |
| Preoperative mechanical circulatory support | 2 (3.4) |
| Mean troponin-T (SD)- ng/mL | 6.8 (13.1) |
| Mean NT-proBNP (SD)- pg/mL | 3446.0 (5652.9) |
| Serum lactate (SD)- mg/dL | 6.6 (4.9) |
| Operative time (min) | 178.6 (34.7) |
| Cardiopulmonary bypass time (min) | 52.6 (17.1) |
| Aortic cross clamp | 43 (72.8) |
| Aortic cross clamp time (min) | 15.9 (16.6) |
| Postoperative complication | 9 (15.3) |
NT-proBNP: N-terminal prohormone of brain natriuretic peptide, SD: Standard deviation, sPESI: Simplified pulmonary embolism severity index, PE: Pulmonary embolism.
Prior to pulmonary embolectomy, 50.8% of patients had right ventricular dysfunction. Preoperative haemodynamic instability was found in 67.8%, and 47.5% of cases developed cardiac arrest. Furthermore, more than half of patients required mechanical breathing support prior to surgery, with mechanical circulatory support reported in 3.4% of cases. For preoperative laboratories, the mean troponin-T was 6.8 ± 13.1 ng/mL, while the mean NT-proBNP was 3446.0 ± 5652.9 pg/mL. The mean serum lactate concentration was 6.6 ± 4.9 mg/mL. Additionally, postoperative complications were found in 15.3%, and the in-hospital mortality was 11.9% (7/59), with the remaining deaths being related to their co-morbid illnesses during follow-up.
Survival analysis
The average follow-up time was 1083.2 ± 1341.1 days, and the mortality rate of this cohort was 15.3%. According to Table 2, the survival probability for seven days, fourteen days, thirty days, and ninety days were, respectively, 91.5% (95% confidence interval (CI) 84.7-98.9), 89.7% (95% CI 82.3-97.9), 86.1% (95% CI 77.5-95.5), and 86.1% (95% CI 77.5-95.5). Moreover, the 1-year and 5-year survival probabilities were 86.1% (95% CI 77.5-95.5). A Cox proportional hazard regression was utilised to explore prognostic factor associations. Body mass index, preoperative mechanical ventilation support, preoperative mechanical circulatory support, and postoperative complications were candidate variables with p <0.1 in the univariate analysis, as shown in Table 3. These candidates were thus examined in multivariable analysis with a backward stepwise approach with the lowest AIC value. Consequently, the final model comprised preoperative mechanical circulatory support (Hazard ratio (HR) 6.03, 95% CI 1.05-34.63) and postoperative complication (HR 26.98, 95% CI 5.36-135.91), as shown in Figure 1.
| Time (day) | Survival probability | 95% confidence interval |
|---|---|---|
| 3 | 91.5 | 84.7-98.9 |
| 5 | 91.5 | 84.7-98.9 |
| 7 | 91.5 | 84.7-98.9 |
| 14 | 89.7 | 82.3-97.9 |
| 30 | 86.1 | 77.5-95.5 |
| 90 | 86.1 | 77.5-95.5 |
| 180 | 86.1 | 77.5-95.5 |
| 360 | 86.1 | 77.5-95.5 |
| 720 | 86.1 | 77.5-95.5 |
| 1800 | 86.1 | 77.5-95.5 |
| Factor | Hazard ratio (95% CI) | p value |
|---|---|---|
| Age-year | 0.98 (0.94-1.03) | 0.42 |
| Sex | ||
| Male | Ref | |
| Female | 1.19 (0.30-4.76) | 0.80 |
| Body mass index -kg/m2 | 1.15 (0.98-1.35) | 0.08 |
| Underlying disease* | ||
| Diabetes mellitus* | 0.97 (0.20-4.71) | 0.97 |
| Hypertension* | 0.83 (0.21-3.34) | 0.79 |
| Cerebrovascular disease* | 2.50 (0.51-12.41) | 0.26 |
| Smoking | ||
| Never | Ref | |
| Active smoking | 0.80 (0.10-6.54) | 0.83 |
| Right ventricular dysfunction* | 0.96 (0.25-3.66) | 0.94 |
| Previous thromboembolism* | 0.66 (0.14-3.17) | 0.60 |
| Haemodynamic instability* | 2.15 (0.43-10.79) | 0.35 |
| Preoperative cardiac arrest* | 2.65 (0.66-10.64) | 0.17 |
| Previous systemic thrombolysis* | 3.70 (0.46-30.12) | 0.22 |
| Previous systemic heparinisation* | 0.52 (0.11-2.53) | 0.42 |
| Preoperative mechanical ventilation support* | 6.74 (0.83-54.95) | 0.07 |
| Preoperative mechanical circulatory support* | 12.03 (2.41-60.14) | 0.002** |
| Troponin-T- ng/mL | 1.00 (0.98-1.02) | 0.55 |
| NT proBNP- pg/mL | 1.00 (0.97-1.03) | 0.65 |
| Serum lactate - mg/dL | 1.09 (0.92-1.28) | 0.31 |
| sPESI | ||
| 0 | Ref | |
| 1-3 |
300076.29 (0.00-1444000) |
0.95 |
| 4 |
127076.07 (0.00-6101440) |
0.94 |
| Operative time (min) | 0.99 (0.98-1.01) | 0.99 |
| Cardiopulmonary bypass time (min) | 1.01 (0.98-1.03) | 0.54 |
| Aortic cross clamp time (min) | 0.99 (0.96-1.03) | 0.59 |
| Postoperative complication | ||
| No | Ref | |
| Yes | 30.36 (6.20-148.56) | <0.001** |
*Data show only “yes group” while reference groups (no group) are hidden. **The significance of p value < 0.05. NT-proBNP: N-terminal prohormone of brain natriuretic peptide, SD: Standard deviation, sPESI: Simplified pulmonary embolism severity index, CI: Confidence interval.
-g1.png)
Kaplan-Meier survival curves of prognostic factors are shown in Figure 2a and b. Patients with preoperative mechanical circulatory support had a significantly poorer prognosis compared to the other group (p <0.001). Patients with postoperative complications had poorer outcomes compared to those without complications (p <0.001).
-g2.png)
DISCUSSION
The present study revealed the long-term outcome of acute PE patients after pulmonary embolectomy. The surgical pulmonary embolectomy prognosis of the present study was comparable to earlier studies. Using survival analysis, Pasrija et al. reported a 1-year survival rate of 91% for PE patients following surgical pulmonary embolectomy, while another study revealed a 5-year survival rate of 78% for patients.[10] Furthermore, the current study’s in-hospital mortality rate was 11.9%, which was close to the study by Dohle et al., which had an in-hospital mortality rate of 19% of cases.[11]
Previous research has reported prognostic factors for PE patients undergoing surgical pulmonary embolectomy, such as age, comorbid conditions, preoperative haemodynamic status, payment type, and hospital type.[7,12] In the present study, the preoperative mechanical circulatory support and postoperative complications are strongly associated with prognosis. In detail, patients who received mechanical circulatory support before the operation had a significantly shorter survival time compared to patients without support. Similarly, Pasrija et al. reported that venoarterial extracorporeal membrane oxygenation is significantly associated with poor prognosis in surgical pulmonary embolectomy.[10] Moreover, patients with surgical complications had a significantly shorter survival time than those without postoperative issues. The explanation for these findings could be that the severity of patients with these factors was higher than that of the other group.
The severity of haemodynamic instability and subtype of acute PE have been associated with mortality following surgical embolectomy, according to prior studies.[10,11] Consequently, haemodynamic factors and subtypes of acute PE were not significantly associated with prognosis, which may be attributed to the study population’s limitations.
Because few studies have examined the long-term prognosis of patients after surgical pulmonary embolectomy, the present investigation found that preoperative mechanical circulatory support and postoperative complications were predictive variables. However, the present study has several limitations. First, the number of patients included in the analysis was relatively limited. Future multicentre studies with larger sample sizes would help increase statistical power and further validate the associations between the identified prognostic factors and clinical outcomes.[16-18] Second, the retrospective design of the study may have introduced potential selection and information biases. Nevertheless, the authors attempted to minimise these biases by establishing predefined operational definitions, as well as clear inclusion and exclusion criteria, before data collection and analysis.[19-21] In addition, the predictive model might be studied and applied in clinical practice to assist physicians with prognostication for surgical pulmonary embolectomy in the future.[22-24]
CONCLUSION
The preoperative mechanical circulatory support and postoperative complications were independent prognostic factors for PE patients who underwent pulmonary embolectomy. The predictive performances of these prognostic factors should be validated in the future.
Ethical approval
The research/study was approved by the Institutional Review Board at Prince of Songkla University, number (REC.67-203-10-4), dated 21st June 2024.
Declaration of patient consent
Patient’s consent is not required as patient’s identity is not disclosed or compromised.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript, and no images were manipulated using AI.
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