Long-Term Outcomes of Abdominal Aortic Aneurysm Repair

Longer follow-up intervals following EVAR are safe and appropriate after marked aneurysm sac regression

BACKGROUND

Abdominal aortic aneurysm (AAA) shrinkage after endovascular aortic aneurysm repair (EVAR) is a surrogate marker for successful exclusion. Our study characterized aneurysm sac remodeling after EVAR to identify a pattern that may be associated with benign AAA behavior and would safely allow a less rigorous follow-up regimen after EVAR.

METHODS

Elective infrarenal EVARs performed between 2008 and 2011 at our institution were retrospectively reviewed. AAA sac diameters using the minor axis measurement from ultrasound imaging or computer tomography angiogram imaging were compared with the baseline diameter from the 1-month postoperative computer tomography angiogram. The primary outcome was a composite of freedom from postoperative reintervention or rupture. We compared those with AAA sacs who regressed to predefined minimum diameter thresholds with those who did not. Outcomes were plotted with Kaplan-Meier curves and compared using log-rank testing and Fine-Gray regression using death as a competing risk, clustered on graft type. For patients whose AAA reached the minimum sac diameter, landmark analysis evaluated ongoing size changes including further regression and sac re-expansion.

RESULTS

A total of 540 patients (aged 75.1 ± 8.2 years; 82.0% male) underwent EVAR with an average preoperative AAA size of 55.2 ± 11.5 mm. The median postoperative follow-up was 5.3 years (interquartile range, 1.4-8.7 years) during which 64 patients underwent reintervention and 4 ruptured. AAA sac regression to ≤40 mm in diameter was associated with improved freedom from reintervention or rupture overall (log-rank, P < .01), which was maintained after controlling for the competing risk of death (P < .01). In 376 patients (70%) whose aneurysm sac remained >40 mm, 99 reinterventions were performed on 63 patients. Of 166 (31%) patients whose sac regressed to ≤40 mm, only 1 patient required a reintervention, and no one ruptured. The mean time to a diameter of ≤40 mm was 2.3 ± 1.9 years. Only eight patients (5%) developed sac re-expansion to >45 mm; all but two occurred at least 3 years after initially regressing to ≤40 mm.

CONCLUSIONS

In long-term follow-up, patients whose minimum AAA sac diameter regressed ≤40 mm after EVAR experienced a very low rate of reintervention, rupture, or sac re-expansion. Most sac re-expansion occurred at least 3 years after reaching this threshold and did not result in clinical events. Increasing follow-up frequency up to 3-year intervals once the AAA sac regresses to 40 mm would carry minimal risk of aneurysm-related morbidity.

Acute Renal Failure/Acute Kidney Injury (AKI) Associated with Endovascular Procedures

AKI is one of the most common yet underdiagnosed postoperative complications that can occur after any type of surgery. Contrast-induced nephropathy (CIN) is still poorly defined and due to a wide range of confounding individual variables, its risk is difficult to determine. CIN mainly affects patients with underlying chronic kidney disease, diabetes, sepsis, heart failure, acute coronary syndrome and cardiogenic shock. Further research is necessary to better understand pathophysiology of contrast-induced AKI and consequent implementation of effective prevention and therapeutic strategies. Although many therapies have been tested to avoid CIN, the only potent preventative strategy involves aggressive fluid administration and reduction of contrast volume. Regardless of surgical technique—open or endovascular—perioperative AKI is associated with significant morbidity, mortality and cost. Endovascular procedures always require administration of a contrast media, which may cause acute tubular necrosis or renal vascular embolization leading to renal ischemia and as a consequence, contribute to increased number of post-operative AKIs.

Association of Hospital Surgical Aortic Valve Replacement Quality With 30-Day and 1-Year Mortality After Transcatheter Aortic Valve Replacement

Importance

Hospital outcomes for transcatheter aortic valve replacement (TAVR) may be dependent on the quality of evaluation, personnel, and procedural and postprocedural care common to patients undergoing cardiac surgery.

Objectives

We sought to assess whether those hospitals with better patient outcomes for surgical aortic valve replacement (SAVR) subsequently achieved better TAVR outcomes after launching TAVR programs.

Design, Setting, and Participants

This national cohort included US patients 65 years and older. The analysis used the Centers for Medicare and Medicaid Services' Medicare Provider and Review data collected between January 1, 2010, and September 29, 2015. Only hospitals performing at least 1 SAVR prior to September 1, 2011, and performing at least 1 TAVR after this date were included in the analysis. Data analysis was completed from June 2018 to August 2018.

Interventions

Isolated aortic valve replacements.

Main Outcomes and Measures

Hospital risk-adjusted 30-day mortality for SAVR in the pre-TAVR period was used as a surrogate for SAVR quality. Thirty-day and 1-year TAVR mortality rates were examined after stratification by quartile of baseline hospital risk-adjusted SAVR mortality.

Results

A total of 51 924 TAVR procedures were performed in 519 hospitals, of which 19 798 were performed at hospitals in quartile 1 (the lowest risk-adjusted SAVR mortality rate), 7663 were performed in quartile 2, 10 180 were performed in quartile 3, and 14 283 were performed in quartile 4 (the highest risk-adjusted SAVR mortality rate). Observed mortality rates at 30 days consistently increased with increasing baseline hospital SAVR risk-adjusted mortality (quartile 1, 917 patients [4.6%]; quartile 2, 381 [5.0%]; quartile 3, 521 [5.1%]; quartile 4, 800 [5.6%]; P < .001). The same pattern was observed in 1-year mortality (quartile 1, 3359 [17.0%]; quartile 2, 1337 [17.5%]; quartile 3, 1852 [18.2%]; quartile 4, 2652 [18.6%]; P < .001). After multivariable analysis, compared with the lowest quartile of SAVR mortality, undergoing TAVR at a hospital with higher baseline SAVR mortality continued to be associated with higher 30-day mortality (odds ratios: quartile 2, 1.02 [95% CI, 0.87-1.21]; quartile 3, 1.13 [95% CI, 1.02-1.26]; quartile 4, 1.23 [95% CI, 1.07-1.40]; P = .02) and 1-year mortality (hazard ratios: quartile 2, 1.04 [95% CI, 0.92-1.17]; quartile 3, 1.14 [95% CI, 1.02-1.28]; quartile 4, 1.16 [95% CI, 1.05-1.28]; P = .02).

Conclusions and Relevance

Hospitals with higher SAVR mortality rates also had higher short-term and long-term TAVR mortality after initiating TAVR programs. Quality of cardiac surgical care may be associated with a hospital's performance with new structural heart disease programs.

Impact of a Claims-Based Frailty Indicator on the Prediction of Long-Term Mortality After Transcatheter Aortic Valve Replacement in Medicare Beneficiaries

Background Prospectively collected frailty markers are associated with an incremental 1-year mortality risk after transcatheter aortic valve replacement (TAVR) compared with comorbidities alone. Whether information on frailty markers captured retrospectively in administrative billing data is similarly predictive of long-term mortality after TAVR is unknown. We sought to characterize the prognostic importance of frailty factors as identified in healthcare billing records in comparison to validated measures of frailty for the prediction of long-term mortality after TAVR. Methods and Results Adult patients undergoing TAVR between August 25, 2011, and September 29, 2015, were identified among Medicare fee-for-service beneficiaries. The Johns Hopkins Claims-based Frailty Indicator was used to identify frail patients. We used nested Cox regression models to identify claims-based predictors of mortality up to 4 years post-procedure. Four groups of variables, including cardiac risk factors, noncardiac risk factors, patient procedural risk factors, and nontraditional markers of frailty, were introduced sequentially, and their integrated discrimination improvement was assessed. A total of 52 338 TAVR patients from 558 clinical sites were identified, with a mean follow-up time period of 16 months. In total, 14 174 (27.1%) patients died within the study period. The mortality rate was 53.9% at 4 years post-TAVR. A total of 34 863 (66.6%) patients were defined as frail. The discrimination of each of the 4 models was 0.60 (95% CI, 0.59-60), 0.65 (95% CI, 0.64-0.65), 0.68 (95% CI, 0.67-0.68), and 0.70 (95% CI, 0.69-0.70), respectively. The addition of nontraditional frailty markers as identified in claims improved mortality prediction above and beyond traditional risk factors (integrated discrimination improvement: 0.019; P<0.001). Conclusions Risk prediction models that include frailty as identified in claims data can be used to predict long-term mortality risk after TAVR. Linkage to claims data may allow enhanced mortality risk prediction for studies that do not collect information on frailty.

Editor's Choice - Re-interventions After Repair of Ruptured Abdominal Aortic Aneurysm: A Report From the IMPROVE Randomised Trial

OBJECTIVE/BACKGROUND

The aim was to describe the re-interventions after endovascular and open repair of rupture, and investigate whether these were associated with aortic morphology.

METHODS

In total, 502 patients from the IMPROVE randomised trial (ISRCTN48334791) with repair of rupture were followed-up for re-interventions for at least 3 years. Pre-operative aortic morphology was assessed in a core laboratory. Re-interventions were described by time (0-90 days, 3 months-3 years) as arterial or laparotomy related, respectively, and ranked for severity by surgeons and patients separately. Rare re-interventions to 1 year, were summarised across three ruptured abdominal aortic aneurysm trials (IMPROVE, AJAX, and ECAR) and odds ratios (OR) describing differences were pooled via meta-analysis.

RESULTS

Re-interventions were most common in the first 90 days. Overall rates were 186 and 226 per 100 person years for the endovascular strategy and open repair groups, respectively (p = .20) but between 3 months and 3 years (mid-term) the rates had slowed to 9.5 and 6.0 re-interventions per 100 person years, respectively (p = .090) and about one third of these were for a life threatening condition. In this latter, mid-term period, 42 of 313 remaining patients (13%) required at least one re-intervention, most commonly for endoleak or other endograft complication after treatment by endovascular aneurysm repair (EVAR) (21 of 38 re-interventions), whereas distal aneurysms were the commonest reason (four of 23) for re-interventions after treatment by open repair. Arterial re-interventions within 3 years were associated with increasing common iliac artery diameter (OR 1.48, 95% confidence interval [CI] 0.13-0.93; p = .004). Amputation, rare but ranked as the worst re-intervention by patients, was less common in the first year after treatment with EVAR (OR 0.2, 95% CI 0.05-0.88) from meta-analysis of three trials.

CONCLUSION

The rate of mid-term re-interventions after rupture is high, more than double that after elective EVAR and open repair, suggesting the need for bespoke surveillance protocols. Amputations are much less common in patients treated by EVAR than in those treated by open repair.

Consideration of Sex Differences in Design and Reporting of Experimental Arterial Pathology Studies-Statement From ATVB Council

There are many differences in arterial diseases between men and women, including prevalence, clinical manifestations, treatments, and prognosis. The new policy of the National Institutes of Health, which requires the inclusion of sex as a biological variable for preclinical studies, aims to foster new mechanistic insights and to enhance our understanding of sex differences in human diseases. The purpose of this statement is to suggest guidelines for designing and reporting sex as a biological variable in animal models of atherosclerosis, thoracic and abdominal aortic aneurysms, and peripheral arterial disease. We briefly review sex differences of these human diseases and their animal models, followed by suggestions on experimental design and reporting of animal studies for these vascular pathologies.