Smoking History Increases the Risk of Long-Term Mortality After Thoracic Endovascular Aortic Repair in Patients with an Uncomplicated Type B Dissection
The optimal treatment for uncomplicated type B aortic dissection remains a subject of debate in the medical community. Traditionally, patients with uncomplicated type B dissections have been managed with optimal medical treatment, which includes blood pressure control and close monitoring. However, emerging evidence suggests that thoracic endovascular aortic repair (TEVAR) may offer superior outcomes, particularly in terms of long-term survival. This study aims to explore the impact of pre-operative smoking history on long-term mortality rates in patients with uncomplicated type B dissections who undergo TEVAR.
Background
Uncomplicated type B aortic dissection involves a tear in the inner layer of the aorta, which allows blood to flow between the layers of the aortic wall. While medical management has been the standard approach, TEVAR has gained traction as a potentially more effective treatment. Since 2001, our center has been performing TEVAR for uncomplicated type B dissections, achieving 5- and 10-year survival rates of 96.5% and 83.0%, respectively. These promising results have led us to advocate for TEVAR as the preferred treatment for this condition.
Smoking is a well-established risk factor for various cardiovascular diseases, including coronary artery disease and aneurysms. It also adversely affects surgical outcomes, increasing the risk of complications and mortality. Despite its known detrimental effects, the specific impact of smoking on long-term survival after TEVAR in patients with uncomplicated type B dissections has not been thoroughly investigated. This study seeks to fill this gap by analyzing the relationship between pre-operative smoking history and long-term mortality in this patient population.
Methods
The study was conducted at Beijing Anzhen Hospital, with data collected from May 2001 to December 2013. A total of 751 patients with uncomplicated type B dissections who underwent TEVAR were included in the analysis. Patients were divided into two groups based on their smoking history: 337 smokers and 414 non-smokers. The primary endpoint was all-cause mortality during follow-up.
The TEVAR procedure followed standard protocols, with pre-operative CT angiography (CTA) used to determine the location of the primary tear and assess the surgical approach. The diameter of the anchoring zone was determined using CTA and aortic angiography, with the stent diameter selected to be 5% to 10% larger than the aortic diameter. The procedure involved the release of the stent and subsequent angiography to confirm proper positioning and sealing of the primary tear. If necessary, additional stents were implanted to address re-ruptures or incomplete expansion of the true lumen.
Follow-up assessments were conducted annually, with patients undergoing aortic CTA and ultrasound to evaluate aortic remodeling and detect any progressive aortic expansion. Patients who could not return to the hospital for follow-up were contacted via telephone or mail to gather relevant information. The follow-up period ended in November 2016, with a median follow-up time of 70 months (range: 1-170 months).
Statistical analysis was performed using the Kaplan-Meier method to compare survival curves between smokers and non-smokers. The log-rank test was used to assess differences in survival rates, and multivariable analyses using the Cox proportional hazards model were conducted to estimate the effects of smoking on survival rates. Variables associated with mortality during follow-up with a P-value < 0.1 in univariate analysis were included in the multivariable analysis.
Results
The study revealed significant differences in long-term survival rates between smokers and non-smokers. The 5- and 10-year survival rates for non-smokers were 97.6% (95% CI: 96.0%-99.2%) and 87.0% (95% CI: 81.6%-92.7%), respectively. In contrast, smokers had 5- and 10-year survival rates of 94.9% (95% CI: 92.2%-97.7%) and 73.8% (95% CI: 62.3%-87.5%), respectively. The log-rank test showed a statistically significant difference in survival rates between the two groups (P = 0.0059).
Multivariable analyses adjusted for age, gender, body mass index (BMI), diabetes, alcohol consumption history, and the number of stents used demonstrated that smoking increased the risk of death during follow-up by 2.1-fold compared to non-smokers (P = 0.039). The study also found that 21 (6.2%) smokers and 21 (5.1%) non-smokers underwent reintervention during the follow-up period, but the difference was not statistically significant (P = 0.486).
Discussion
The findings of this study underscore the detrimental impact of pre-operative smoking history on long-term survival after TEVAR in patients with uncomplicated type B dissections. Smoking is an independent risk factor for cardiovascular diseases, and its adverse effects on surgical outcomes are well-documented. However, the specific mechanisms by which smoking increases long-term mortality in this patient population remain unclear.
One possible explanation is that smoking may increase the risk of residual dissection distal to the stent, leading to a higher likelihood of aortic rupture. Additionally, smokers often have more severe aortic atherosclerosis and calcifications, which reduce aortic compliance and increase the risk of residual dissection rupture. Smoking is also associated with other cardiovascular diseases, such as coronary artery disease, which can contribute to increased mortality.
The study’s results align with previous research indicating that smoking cessation can significantly reduce the risk of cardiovascular diseases. For instance, a study on abdominal aortic aneurysms found that the risk of aneurysm formation in former smokers equaled that of non-smokers 25 years after quitting smoking. This highlights the importance of smoking cessation programs, particularly for patients undergoing TEVAR.
Limitations
This study has several limitations. It is a retrospective analysis, and the degree of smoking was not classified, which means the impact of mild versus severe smoking on long-term survival could not be assessed. Additionally, the study did not differentiate between patients who quit smoking before or after TEVAR and those who continued to smoke. Future research should address these limitations to provide a more comprehensive understanding of the relationship between smoking and long-term outcomes after TEVAR.
Conclusion
In conclusion, pre-operative smoking history significantly increases the risk of long-term mortality after TEVAR in patients with uncomplicated type B dissections. The 5- and 10-year survival rates for smokers were notably lower than those for non-smokers, and multivariable analyses confirmed that smoking increased the risk of death during follow-up by 2.1-fold. These findings emphasize the importance of smoking cessation programs for patients undergoing TEVAR and highlight the need for further research to elucidate the mechanisms underlying the adverse effects of smoking on long-term survival.
doi.org/10.1097/CM9.0000000000000640
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