Machine learning-based prediction of abdominal aortic aneurysms for individualized patient care.

OBJECTIVE: The United States Preventative Services Task Force guidelines for screening for abdominal aortic aneurysms (AAA) are broad and exclude many at risk groups. We analyzed a large AAA screening database to examine the utility of a novel machine learning (ML) model for predicting individual risk of AAA. METHODS: We created a ML model to predict the presence of AAAs (>3 cm) from the database of a national nonprofit screening organization (AAAneurysm Outreach). Participants self-reported demographics and comorbidities. The model is a two-layered feed-forward shallow network. The ML model then generated AAA probability based on patient characteristics. We evaluated graphs to determine significant factors, and then compared those graphs with a traditional logistic regression model. RESULTS: We analyzed a cohort of 10,033 patients with an AAA prevalence of 2.74%. Consistent with logistic regression analysis, the ML model identified the following predictors of AAA: Caucasian race, male gender, advancing age, and recent or past smoker with recent smoker having a more profound affect (P < .05). Interestingly, the ML model showed body mass index (BMI) was associated with likelihood of AAAs, especially for younger females. The ML model also identified a higher than predicted risk of AAA in several groups, including female nonsmokers with cardiac disease, female diabetics, those with a family history of AAA, and those with hypertension or hyperlipidemia at older ages. An elevated BMI conveyed a higher than expected risk in male smokers and all females. The ML model also identified a complex relationship of both diabetes mellitus and hyperlipidemia with gender. Family history of AAA was a more important risk factor in the ML model for both men and women too. CONCLUSIONS: We successfully developed an ML model based on an AAA screening database that unveils a complex relationship between AAA prevalence and many risk factors, including BMI. The model also highlights the need to expand AAA screening efforts in women. Using ML models in the clinical setting has the potential to deliver precise, individualized screening recommendations.

Evaluating the prevalence of abdominal aortic aneurysms in the United States through a national screening database.

OBJECTIVE: The U.S. Preventative Services Task Force guidelines for abdominal aortic aneurysm (AAA) screening are based mainly on studies of older Caucasian males from non-U.S. POPULATIONS: This study was designed to analyze the findings of a large, all-inclusive AAA screening program in the United States. METHODS: Screening events were held nationally by a U.S. nonprofit organization between 2001 and 2017. AAA screening was offered regardless of risk profile. Participants filled out a demographics form with known comorbidities. Significant risk factors were determined using logistic regression with backward stepwise variable selection. Odds ratios (OR) are reported with 95% confidence intervals (CIs). RESULTS: A total of 9457 screened participants (47% male) were analyzed. The mean age was 67 ± 9 years with 40.8% between 65 and 75 years old. Most participants were Caucasian (83.4%), followed by African American (13.1%). Screened risk factors included hypertension (58.1%), hyperlipidemia (54.9%), smoking (52.0%), cardiac disease (29.2%), diabetes mellitus (18.4%), a family history of AAA (22.4%) or brain aneurysms (8.6%), and body mass index (26.9 ± 5.28). Overall, 267 participants (2.82%) were found to have an AAA (>3 cm). Those ages 65 to 75 had a prevalence of 2.98%. In a fully adjusted, multivariate logistic regression, there was an increased risk of AAA in males (OR, 3.24; 95% CI, 2.39-4.40), current smokers (OR, 3.28; 95% CI, 2.36-4.54), previous smokers (OR, 1.86; 95% CI, 1.41-2.47), cardiac disease (OR, 1.30; 95% CI, 1.01-1.68), family history of AAA (OR, 1.60; 95% CI, 1.20-2.14), and advancing age (P < .0001). Female ever smokers 65 to 75 years old had a prevalence of 1.7%. Male smokers 45 to 54 and 55 to 64 years old had a prevalence of 3.37% and 4.43%, respectively. There was an increased risk of AAA in females with morbid obesity (OR, 5.54; 95% CI, 1.34-22.83 in never smokers and OR, 5.61; 95% CI, 1.04-30.15 in smokers), female smokers with hypertension (OR, 3.22; 95% CI, 1.21-8.58), males with cardiac disease (OR, 2.06; 95% CI, 1.08-3.90 in never smokers and OR, 1.48; 95% CI, 1.05-2.09), male smokers with a family history of AAA (OR, 1.69; 95% CI, 1.61-2.46), and current smokers (OR, 6.33; 95% CI, 2.62-15.24 for females and OR, 2.50; 95% CI, 1.70-3.65 for males). CONCLUSIONS: This study shows that there remain high-risk groups outside the current guidelines that would likely benefit from AAA screening. Risk factors for AAA include male gender, smoking, cardiac disease, family history of AAA, and advancing age. The most significant risk factor is current smoking status.

Aortic arch and descending thoracic aortic aneurysms: experience with stent grafting for second-stage "elephant trunk" repair.

Reconstruction of aortic arch and descending thoracic aortic aneurysms (TAAs) is technically challenging and associated with significant morbidity and mortality. We report our experience with extensive TAAs using a two-stage "elephant trunk" repair, with the second stage completed using an endovascular stent graft (ESG). Over 6 years, 111 patients underwent ESG treatment of TAAs at Mount Sinai Medical Center. Twelve of these patients were referred for ESG placement for the second stage of elephant trunk reconstruction because comorbidities placed them at high risk of open surgical repair. Our database was analyzed for technical and clinical success and perioperative complications. The mean follow-up was 11.8 months (range 1-64 months). Twelve patients (five women and seven men) with a mean age of 69 +/- 10 years underwent repair of their distal aortic arch and descending TAAs. These aneurysms included nine atherosclerotic aneurysms, one pseudoaneurysm, and two penetrating atherosclerotic ulcers. Three patients were symptomatic. Stent graft repair was technically successful in 91.7% or 11 of 12 patients. Excessive aortic arch tortuosity resulted in failure to deploy a stent graft in one patient. An antegrade approach through the open elephant trunk was used in two patients with severe iliac occlusive disease. Endoleaks (type 2) were identified in two patients with no aneurysm expansion; however, a 14 mm expansion over 1 year occurred in a patient with no identifiable endoleak. One early mortality occurred in a patient with a ruptured 6 cm infrarenal AAA after successful exclusion of the 8 cm TAA. Second-stage elephant trunk reconstruction of an extensive TAA using an ESG is effective in the short term. Its long-term durability remains to be determined.

First experience in human beings with a permanently implantable intrasac pressure transducer for monitoring endovascular repair of abdominal aortic aneurysms.

OBJECTIVES: Endovascular stent graft repair of abdominal aortic aneurysms (AAAs) prevents rupture by excluding the aneurysm sac from systemic arterial pressure. Current surveillance protocols after endovascular aneurysm repair (EVAR) follow secondary markers of sac pressurization, namely, endoleak and sac enlargement. We report the first clinical experience with the use of a permanently implantable, ultrasound-activated remote pressure transducer to measure intrasac pressure after EVAR. METHODS: Over 7 months, 14 patients underwent EVAR of an infrarenal abdominal aortic aneurysm with implantation of an ultrasound-activated remote pressure transducer fixed to the outside of the stent graft and exposed to the excluded aortic sac. Twelve patients received modular bifurcated stent grafts, and 2 patients received aortouniiliac devices. Intrasac pressures were measured directly with an intravascular catheter and by the remote sensor at stent-graft deployment. Follow-up sac pressures were measured with a remote sensor and correlated with systemic arterial pressure at every follow-up visit. Mean follow-up was 2.6 +/-1.9 months. RESULTS: Excellent concordance was found between catheter-derived and transducer-derived intrasac pressssure intraoperatively. Pulsatile waveforms were seen in all functioning transducers at each evaluation interval. One implant ceased to function at 2 months of follow-up. In 1 patient a type I endoleak was diagnosed on 1-month computed tomography (CT) scans; 3 type II endoleaks were observed. Those patients with complete exclusion of the aneurysm on CT scans had a significant difference in systemic and sac systolic pressures initially (P <.001) and at 1 month (P <.001). Initial sac diastolic pressures were higher than systemic diastolic pressures (P <.001). The ratio of systemic to sac systolic pressure increased over time in those patients with complete aneurysm exclusion ( P <.001). Four of 6 patients with no endoleak and greater than 1-month follow-up had diminution of sac systolic pressure to 40 mm Hg or less by 3 months. CONCLUSION: This is the first report of a totally implantable chronic pressure transducer to monitor the results of EVAR in human beings. Aneurysm exclusion leads to gradual diminution of sac pressure over several months. Additional clinical follow-up will be necessary to determine whether aneurysm sac pressure monitoring can replace CT in the long-term surveillance of patients after EVAR.

The role of aortic stent grafting in the treatment of atheromatous embolization syndrome: results after a mean of 15 months follow-up.

BACKGROUND: Endovascular stent-graft (ESG) repair of abdominal aortic aneurysm (AAA) has emerged as an alternative to open surgery. The role of ESG in patients with challenging medical and anatomic problems remains an area of general debate. This study reviews an experience with stent grafts to treat patients with AAA and atheromatous embolization syndrome (AES) presenting with chronic distal embolization (CDE). METHODS: Over a 5-year period 660 patients with AAA were treated with aortic stent grafts. Patients with AAA and ischemic ulcerations or toe gangrene due to CDE despite palpable foot pulses were investigated for successful aneurysm exclusion, resolution of ischemic symptoms, complications and survival. Follow-up averaged 15.3 +/- 14.9 months (range, 1 to 60 months). RESULTS: Nineteen patients had AAA and manifestations of CDE. The population (16 males/3 females) had a mean age of 79 +/- 7 years and mean aneurysm diameter of 5.5 cm. Renal insufficiency was present in 5/19 (26 %). Ischemia presented as ischemic ulcers (16/19 [84.2%]) or toe gangrene (3/19 [15.8%]). Stent grafts included 6 aortouniiliac and 13 bifurcated devices. Exclusion was achieved in all but 2 patients who had type II lumbar endoleaks. At 30-day postoperative follow-up, mortality was 0 % and resolution of CDE/ischemia was noted in 2 of 19 (10.5%) patients. Eight of 9 patients with follow-up of 1 year had complete resolution of their ischemic symptoms, with no recurrent manifestations of AES. Complications included progression of renal insufficiency over an 18-month period in 1 patient and an unstable expanding pararenal aortic neck in 1 patient. Foot ischemia persisted at 1 year in a patient with severe coexisting thoracic aortic disease despite successful AAA exclusion. Six (31.6%) patients died during a mean follow-up of 15.3 months from causes unrelated to their AAA. CONCLUSION: On the basis of this experience, stent-graft repair of AAA and CDE may be an effective strategy to prevent future embolization. Recognition of coexisting thoracic aortic disease is essential. ESG does not address the extremely high morbidity and mortality from cardiovascular causes in this population.

Endovascular stent graft repair of abdominal and thoracic aortic aneurysms: a ten-year experience with 817 patients.

OBJECTIVE: On November 23, 1992, the first endovascular stent graft (ESG) repair of an aortic aneurysm was performed in North America. Following the treatment of this patient, we have continued to evaluate ESG over the past 10 years in the treatment of 817 patients. SUMMARY AND BACKGROUND DATA: Abdominal (AAA) or thoracic (TAA) aortic aneurysms are a significant health concern traditionally treated by open surgical repair. ESG therapy may offer protection from aneurysm rupture with a reduction in procedure morbidity and mortality. METHODS: Over a 10-year period, 817 patients were treated with ESGs for AAA (723) or TAA (94). Patients received 1 of 12 different stent graft devices. Technical and clinical success of ESGs was reviewed, and the incidence of procedure-related complications was analyzed. RESULTS: The mean age was 74.3 years (range, 25-95 years); 678 patients (83%) were men; 86% had 2 or more comorbid medical illnesses, 67% of which included coronary artery disease. Technical success, on an intent-to-treat basis was achieved in 93.8% of patients. Primary clinical success, which included freedom from aneurysm-related death, type I or III endoleak, graft infection or thrombosis, rupture, or conversion to open repair was 65 +/- 6% at 8 years. Of great importance, freedom from aneurysm rupture after ESG insertion was 98 +/- 1% at 9 years. There was a 2.3% incidence of perioperative mortality. One hundred seventy five patients died of causes not related to their aneurysm during a mean follow-up of 15.4 months. CONCLUSIONS: Stent graft therapy for aortic aneurysms is a valuable alternative to open aortic repair, especially in older sicker patients with large aneurysms. Continued device improvements coupled with an enhanced understanding of the important role of aortic pathology in determining therapeutic success will eventually permit ESGs to be a more durable treatment of aortic aneurysms.