Emergency department imaging utilization post-transcatheter aortic valve replacement: single institution 7-year experience

Purpose This study aims to highlight presentations, acute findings and imaging phenotypes of patients presenting to the emergency department (ED) within 30 days of a transcatheter aortic valve replacement (TAVR). Methods A retrospective review of patients diagnosed with aortic valve disease who underwent a TAVR between Jan 2015 and Nov 2021 at a large academic medical center was completed. From an initial 1271 patients, 146 were included based on their presentation to the ED within 30 days post-TAVR procedure. Patient data, including ED presentation details and imaging results, were recorded and de-identified. Results Of the 146 post-TAVR patients, there were 168 ED visits within 30 days. The median time to ED after TAVR was 12 days. Respiratory symptoms were the most common complaint (27%). Neurological (23%) and cardiovascular symptoms (18%) followed. Cross-sectional imaging was conducted 250 times across visits, with an average of 1.7 scans per patient. CTs were most frequently used, followed by ultrasounds, especially echocardiograms and duplex extremity vasculature ultrasounds. 30.1% of patients had acute findings from imaging. Specific findings included heart failure (5.5%), access site complications (5.5%), pneumonia (5.5%), intracranial pathologies (3.4% for strokes and 0.7% for hematoma), and pleural effusion (3.4%). Echocardiograms and CTA chest were most associated with significant acute findings. Conclusion Our study highlights the vital role of early and accurate imaging in post-TAVR patients within 30 days post-procedure. As transcatheter approaches rise in popularity, emergency radiologists become instrumental in diagnosing common post-procedural presentations. Continued research is essential to devise post-discharge strategies to curtail readmissions and related costs. Proper imaging ensures prompt, effective care, enhancing overall patient outcomes.


Introduction
In the turn of the century, transcatheter aortic valve replacement (TAVR) has gradually overtaken surgical aortic valve replacement (SAVR) as the leading intervention for patients with aortic stenosis. 1While the rates of procedural success complications in the post cardiac valve surgeries patient population 5 , this study aims to shed light on the trends in presentation common to the post TAVR population, specifically within the first 30 days post-procedure.
Given the advanced age of most patients undergoing TAVR and the sizable and growing quantity of TAVR procedures carried out annually in the US (72,991 in 2019) 1 , emergency radiologists will be the first to interpret various ED imaging and must be prepared for the growing number and imaging nuances of post-TAVR patients.Because the Center for Medicare and Medicaid Services continues to utilize readmission as a quality metric that affects reimbursement, it is imperative for emergency personnel to be familiar with trends of ED presentation especially in the critical 30 day post-procedural period.Additionally, with the growing importance of cognizant healthcare spending, we believe it necessary to simultaneously explore the financial impact of imaging in this patient population.
The goal of this study is to first inform radiologists of common imaging needed in the post-TAVR population within the 30 day post-procedural period and common presenting symptoms and acute imaging findings to be on the lookout for.We will then analyze the subsequent costs of the necessary imaging.

Materials and methods
After retrospective review of the hospital electronic medical record (EMR), patients with a diagnosis of aortic valve disease that were evaluated for and received a TAVR at a large academic medical center between Jan 2015 and Nov 2021 were included in this study.The study protocol was approved by the institutional review board of our institution, and all patients have provided prior informed consent for the imaging that they received.The study group was made up of an initial 1271 patients prior to inclusion and exclusion criteria.Our group of interest included patients who presented to the ED within 30 days of their TAVR procedure.With this criteria, 146 patients were included in our study (Fig. 1).
Information related to patient ED presentation was recorded and de-identified.This included date of presentation, length of stay, reason for presentation, indication for imaging, imaging obtained, imaging findings, and any resulting diagnoses.This was confirmed via supporting evidence located in physician notes in the EMR and were further categorized based on malignancy when relevant.
A radiologist-in-training in collaboration with a fellowship trained radiologist (21 years of experience) then reviewed cross-sectional imaging findings to confirm their correlation with the final diagnoses that were documented by the ED team or primary team.Cross-sectional imaging obtained in the ED including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), image guided procedures and nuclear medicine ventilation-perfusion (VQ) scans, were recorded.

Patient demographics
Our study population consisted of 146 patients with a diagnosis of aortic stenosis and an ED presentation within 30 days of their TAVR procedure.The demographics of our study were made up of mostly geriatric patients with an average age of 79.7 (median 79.7 years, interquartile range 72.5-86.6).Male patients made up a larger portion of the study population at 61% compared to the female patients at 39%.
Among our 146 patients, there was a collective total of 168 ED visits within 30 days of the TAVR procedure.124 patients (85%) visited the ED once and 22 (15%) visited the ED twice within this time frame.Among these 168 total ED visits, 117 (70%) resulted in admission to an inpatient service.The median time from the TAVR procedure to ED presentation was 12 days, with a range of 2 to 30 days and an interquartile range of 6 to 21 days.The median length of hospital stay upon ED presentation was 2 days, with a range of 0 to 34 days and an interquartile range of 0 to 4 days.Of all patients who presented to the ED, 7 (4.8%)passed away during their hospital stay (Table 1).
On chart review, the most commonly cited indications for imaging during the ED visit or during their subsequent readmission included dyspnea, fall, chest pain, head injury/ trauma and syncope.Neurologic indications for imaging were the most common in this population (n = 52) followed by vascular indications (n = 37) and cardiac indications (n = 25) (Table 3).While never mentioned as a sole indication for cross-sectional imaging, post-TAVR status was often included alongside other indications.
A total of 250 cross-sectional imaging examinations were obtained across all ED visits for the included 146 patients, with an average of 1.7 examinations per patient (Table 4).The most common imaging modality utilized was CTs (n = 129).CT examinations ordered include CT head (n = 39), CTA Chest (n = 26) CT abdomen and pelvis (A/P) with contrast (n = 16), CT chest without contrast (n = 24) and C-spine without contrast [11].Ultrasounds were the second most common type of cross-sectional imaging ordered (n = 101).The 2 most common ultrasound modalities were echocardiograms (n = 47) and duplex extremity vasculature  10) *some visits had multiple presenting symptoms.Common symptoms are not all-inclusive of all presenting symptoms (Figs.6), 1 pseudoaneurysm (Figs.7) and 1 femoral artery thrombus.Most commonly, these patients reported some form of localized groin (swelling, infection, bleeding) or leg symptoms (leg pain, swelling).However, some presented with non-specific signs such as GI discomfort (abdominal pain, nausea, vomiting, diarrhea) or weakness.Of note, 1 case of pneumonia was also found on abdominal imaging.
The most common imaging finding from cardiac imaging (ECHO) was heart failure.There were 8 total cases in this population.The most common patient presentation was shortness of breath, which was found in 5 of 8 patients.Other presenting symptoms included hypotension, fatigue, abnormal ICD firing, chest pain, and hyponatremia.
In imaging of the extremities such as duplex ultrasounds (n = 40) and extremity MRI (n = 1), common imaging findings include 1 deep vein thrombosis and 4 access site complications: 3 cases of access site hematoma and one access site thrombus.These patients commonly presented with localized leg swelling or pain.
There were 47 acute findings overall from the imaging that were obtained.Of note, 3 patients had 2 acute findings each.In total, 44 of the 146 patients (30.1%) were found to have acute findings.
Common imaging findings from chest imaging included 7 cases of pneumonia and 4 pleural effusions.Presenting symptoms varied widely from patient to patient for pneumonia, with no clear trend (Fig. 2).The most common presenting symptom was shortness of breath for patients with pleural effusions, present in 4 of 5 patients (Fig. 3).Of note, 1 case of pleural effusion was found on abdominal imaging.
Head and neck imaging findings included 4 cases of stroke and 1 brain hematoma.Altered mental status was the predominant presenting symptom, which was found in 4 of 5 patients (Figs. 4 and 5).
When it came to abdominal imaging, these included 1 gastrointestinal bleed and 4 access site complications: 1 access site hematoma, 1 case of necrotizing fasciitis as the most common categories of presenting symptoms, neurologic and vascular indications prevailed as the most common categories for imaging indication.Thus, common presenting symptoms do not necessarily translate to common indications for imaging in this patient population.
This study also found that CTs and ultrasounds were the 2 most commonly utilized cross-sectional imaging modalities in the post-TAVR patient population.While echocardiograms and duplex extremity vasculature ultrasounds were the most abundant types of studies ordered with 47 and 40 studies respectively, CTA chest and echocardiograms were the 2 study modalities that most commonly resulted in acute findings of significance with 12 and 8 findings respectively.Echocardiograms consistently pinpointed heart failure symptoms and complications.Chest CT angiograms, from 26 scans, yielded significant findings in 12 patients, 10 of whom had pulmonary findings including but not limited to pneumonia and pleural effusions, and 2 of whom had aortic findings such as an aortic aneurysm or a hematoma surrounding the aorta.This reinforces the vital role of these imaging of studies ordered with 47 and 40 studies respectively, CTA chest and echocardiograms were the 2 study modalities that most commonly resulted in acute findings of significance with 12 and 8 findings respectively (Table 5).

Discussion
This study aims to report on trends in multi-modality emergency department cross-sectional imaging in the post-TAVR patient population within 30 days of their TAVR procedure.Among the 146 patients included in this study, there were 168 ED visits where 22 patients had 2 visits within this time span.While the most prevalent presenting symptoms were respiratory symptoms, mentioned in 45 of the 168 total visits (27%), and neurological symptoms, reported in 38 of the 168 total visits (23%), the most common acute findings of this patient population were heart failure (5.5%), pneumonia (5.5%), access site complications (5.5%), cerebrovascular events (3.4%) and pleural effusions (3.4%).Furthermore, while respiratory and neurological symptoms prevailed Similar to existing literature, this study found that readmissions within 30 days of the index admission were more likely due to non-cardiac related causes rather than cardiac-related causes 7,8 .Kolte et al. analyzed data from the 2013 US NRD and showed an all-cause readmission rate of 17.9%, with only 38.2% of readmissions due to cardiovascular causes.The authors noted that there was a median cost of $8,302 per patient for post-TAVR 30-day readmissions.In their study, heart failure was also the most common cause of all-cause readmission in 22.5% of the cases. 7omparably, Zahid et al. 9 .found 3.6% of 30-day readmissions attributed to heart failure.Other studies also found that congestive heart failure and arrhythmias were the most common cardiac causes of 30-day readmission. 10mong non-cardiac causes, respiratory, infectious, bleeding and vascular conditions have been identified as the most common causes of 30-day readmission.This is comparable to our results where pneumonia (5.5%) and access site complications (5.5%) were the top non-cardiac findings within this patient population.In a study by Arora et al. 11 , they showed that the cost of an average 30-day TAVR readmission was $10,068, with no significant differences in 2012-17while the cost burden of readmissions for every techniques in identifying key post-operative complications  85% of which were within 1 week of the procedure 12 .The most common presenting symptom for stroke in our study population was altered mental status, which resulted in a diagnosis of stroke in 4 of 6 patients that presented with this symptom.Given these statistics, it is important for radiologists to recognize this trend and be especially vigilant about signs of stroke in the immediate post-procedural timeframe.
In the post-op setting of TAVR procedures, the potential diagnoses of stroke and heart failure (HF) -both associated with diminished one-year survival rates 11 -necessitate increased diagnostic vigilance when patients present to the ED.Among the scans conducted in our cohort, non-contrast CT or MRI brain was instrumental in diagnosing cerebrovascular events.Of the 39 head CTs, 4 revealed critical findings such as strokes and a brain hematoma while 1 of 4 head MRIs revealed a stroke.Echocardiography stood out as the definitive modality for diagnosing heart failure, with 8 out of 47 echocardiograms revealing acute results.For clinicians, recognizing the urgency of timely imaging and diagnosis is vital, and the choice of imaging technique should be informed by the most likely clinical in conjunction the ACR Appropriateness Criteria guidelines.
There are a few limitations in our study.First, the study is retrospective in nature.Secondly, the study comprises patients from a single institution which limits the sample size of the study, which may not be representative of broader TAVR populations, particularly those in other healthcare settings or geographical locations.Thirdly, the accuracy of TAVR performed was $1,883 in 2017, which had significantly declined from $4,061 in 2012.
Examining TAVR readmission trends as a whole, it seems that despite all-cause readmissions decreasing significantly over the years (2015-2018), 30-day HF (heart failure) readmissions after TAVR remained steady.Moreover, HF readmissions were associated with increased mortality and resource use compared with non-HF readmission 9 .Given each HF readmission within 30 days is associated with an average increased cost of $13,000 more than for each non-HF readmission, focus on early recognition and complication prevention of HF in this post-operative patient population continues to be crucial 9 .Because HF readmission mortality has remained relatively unchanged over the years 9 , a low threshold for advising further testing and imaging for HF will likely benefit many patients.Methods such as suggesting echocardiograms and correlation with clinical data when signs of HF are apparent on cross-sectional imaging may be helpful.We also advocate for further research in developing post discharge interventions for this cohort to help mitigate the risk of readmissions and consequently reduce overall costs.
While not the most common acute imaging finding in in this study, post procedural strokes within the post procedural 30-day period are also prevalent at 2.7% of acute imaging findings.In the PARTNER trial, which included the continued access registry with 2621 patients, within 30 days of TAVR, 87 (3.3%) patients experienced a stroke, Fig. 7 88 year old male with history of cerebral vascular accident presenting with nausea and vomiting.CT abdomen and pelvis in soft tissue window in Axial (A) and sagittal (B) reformats demonstrate a 1.4 cm hyperdensity (blue arrow) anteriorly at the left common femoral artery, most consistent with a pseudoaneurysm and heterogeneous density surrounding left common femoral vessels, suggestive of hematoma

Conclusion
In conclusion, this research underscores the importance of early and precise imaging in diagnosing and managing post-TAVR patients within 30 days of their index admission.Future research is warranted to develop post-discharge interventions that can potentially reduce readmission rates and the associated healthcare costs.Given the results of our study, it is apparent that emergency radiologists play a crucial role in the diagnostic evaluation of acute presentations in this patient population.As the utilization of transcatheter approaches to aortic valve replacement increases with the aging population and emergency visits post-TAVR remains high, emergency radiologists need to be aware of the common imaging presentations in this post-procedural population as well as recommend appropriate followup imaging.Ultimately, proper imaging guidance can ensure that post-TAVR patients receive timely and effective care, thereby improving their overall outcomes.

Fig. 3
Fig. 3 84 year old female with history of Monckeberg's arteriosclerosis presenting with shortness of breath.Axial CT images in lung window shows (A) pleural effusion (orange arrow) and (B) interlobular septal thickening and ground glass opacities (blue arrows) representing pulmonary edema

Fig. 6
Fig. 6 69 year old female presenting with infected groin wound.Axial CT images of the pelvis in soft tissue window demonstrate (A) fat stranding and foci of air in the left lower abdominal wall, demonstrating necrotizing fasciitis.(B) Post treatment CT pelvis in soft tissue window resolution of necrotizing fasciitis status-post debridement and repair of the left inguinal area

Fig. 5
Fig. 5 81 year old female with a history of peripheral vascular disease presenting with toe pain in bilateral feet.(A) Axial CT head 26 days prior to ED visit demonstrating loss of gray-white differentiation in the medial left occipital lobe, consistent with acute to subacute left PCA territory infarction.(B) On presentation Axial CT head demonstrates evolution of a left occipital subacute infarction, larger and more discrete appearing than previously, also now with petechial hemorrhage

Table 3
Common cross-sectional imaging indications*