Uncovering the treatable burden of severe aortic stenosis in Australia: current and future projections within an ageing population

Incidence and Predictors of Readmissions to Non-Index Hospitals After Transcatheter Aortic Valve Implantation in the Contemporary Era in New South Wales, Australia

BACKGROUND

In Australia, transcatheter aortic valve implantation (TAVI) is only performed in a limited number of specialised metropolitan centres, many of which are private hospitals, making it likely that TAVI patients who require readmission will present to another (non-index) hospital. It is important to understand the impact of non-index readmission on patient outcomes and healthcare resource utilisation.

METHOD

We analysed linked hospital and death records for residents of New South Wales, Australia, aged ≥18 years, who had an emergency readmission within 90 days following a TAVI procedure in 2013-2022. Mixed-effect, multi-level logistic regression models were used to evaluate predictors of non-index readmission, and associations between non-index readmission and readmission length of stay, 90-day mortality, and 1-year mortality.

RESULTS

Of 4,198 patients (mean age, 82.7 years; 40.6% female) discharged alive following TAVI, 933 (22.2%) were readmitted within 90 days of discharge. Over three-quarters (76.0%) of those readmitted returned to a non-index hospital, with no significant difference in readmission principal diagnosis between index hospital and non-index hospital readmissions. Among readmitted patients, independent predictors of non-index readmission included: residence in regional or remote areas, lower socio-economic status, having a pre-procedure transfer, and a private index hospital. Readmission length of stay (median, 4 days), 90-day mortality (adjusted odds ratio [OR] 1.04, 95% confidence interval [CI] 0.56-1.96) and 1-year mortality (adjusted OR 1.01, 95% CI 0.64-1.58) were similar between index and non-index readmissions.

CONCLUSIONS

Non-index readmission following TAVI was highly prevalent but not associated with increased mortality or healthcare utilisation. Our results are reassuring for TAVI patients in regional and remote areas with limited access to return to index TAVI hospitals.

Severe aortic stenosis: secular trends of incidence and outcomes

BACKGROUND AND AIMS

Severe aortic stenosis (AS) is the guideline-based indication for aortic valve replacement (AVR), which has markedly increased with transcatheter approaches, suggesting possible increasing AS incidence. However, reported secular trends of AS incidence remain contradictory and lack quantitative Doppler echocardiographic ascertainment.

METHODS

All adults residents in Olmsted County (MN, USA) diagnosed over 20 years (1997-2016) with incident severe AS (first diagnosis) based on quantitatively defined measures (aortic valve area ≤ 1 cm2, aortic valve area index ≤ 0.6 cm2/m2, mean gradient ≥ 40 mmHg, peak velocity ≥ 4 m/s, Doppler velocity index ≤ 0.25) were counted to define trends in incidence, presentation, treatment, and outcome.

RESULTS

Incident severe AS was diagnosed in 1069 community residents. The incidence rate was 52.5 [49.4-55.8] per 100 000 patient-year, slightly higher in males vs. females and was almost unchanged after age and sex adjustment for the US population 53.8 [50.6-57.0] per 100 000 residents/year. Over 20 years, severe AS incidence remained stable (P = .2) but absolute burden of incident cases markedly increased (P = .0004) due to population growth. Incidence trend differed by sex, stable in men (incidence rate ratio 0.99, P = .7) but declining in women (incidence rate ratio 0.93, P = .02). Over the study, AS clinical characteristics remained remarkably stable and AVR performance grew and was more prompt (from 1.3 [0.1-3.3] years in 1997-2000 to 0.5 [0.2-2.1] years in 2013-16, P = .001) but undertreatment remained prominent (>40%). Early AVR was associated with survival benefit (adjusted hazard ratio 0.55 [0.42-0.71], P < .0001). Despite these improvements, overall mortality (3-month 8% and 3-year 36%), was swift, considerable and unabated (all P ≥ .4) throughout the study.

CONCLUSIONS

Over 20 years, the population incidence of severe AS remained stable with increased absolute case burden related to population growth. Despite stable severe AS presentation, AVR performance grew notably, but while declining, undertreatment remained substantial and disease lethality did not yet decline. These population-based findings have important implications for improving AS management pathways.

Value Creation Through Artificial Intelligence and Cardiovascular Imaging: A Scientific Statement From the American Heart Association

Multiple applications for machine learning and artificial intelligence (AI) in cardiovascular imaging are being proposed and developed. However, the processes involved in implementing AI in cardiovascular imaging are highly diverse, varying by imaging modality, patient subtype, features to be extracted and analyzed, and clinical application. This article establishes a framework that defines value from an organizational perspective, followed by value chain analysis to identify the activities in which AI might produce the greatest incremental value creation. The various perspectives that should be considered are highlighted, including clinicians, imagers, hospitals, patients, and payers. Integrating the perspectives of all health care stakeholders is critical for creating value and ensuring the successful deployment of AI tools in a real-world setting. Different AI tools are summarized, along with the unique aspects of AI applications to various cardiac imaging modalities, including cardiac computed tomography, magnetic resonance imaging, and positron emission tomography. AI is applicable and has the potential to add value to cardiovascular imaging at every step along the patient journey, from selecting the more appropriate test to optimizing image acquisition and analysis, interpreting the results for classification and diagnosis, and predicting the risk for major adverse cardiac events.

Dietary Vitamin K1 Intake and Incident Aortic Valve Stenosis

BACKGROUND

Leaflet calcification contributes to the development and progression of aortic valve stenosis. Vitamin K activates inhibitors of vascular calcification and may modulate inflammation and skeletal bone loss. Therefore, we aimed to determine whether higher dietary intakes of vitamin K1 are associated with a lower incidence of aortic stenosis.

METHODS

In the Danish Diet, Cancer and Health study, participants aged 50 to 64 years completed a 192-item food frequency questionnaire at baseline, from which habitual intakes of vitamin K1 were estimated. Participants were prospectively followed using linkage to nationwide registers to determine incident aortic valve stenosis (primary outcome) and aortic stenosis with subsequent complications (aortic valve replacement, heart failure, or cardiovascular disease-related mortality; secondary outcome).

RESULTS

In 55 545 participants who were followed for a maximum of 21.5 years, 1085 were diagnosed with aortic stenosis and 615 were identified as having subsequent complications. Participants in the highest quintile of vitamin K1 intake had a 23% lower risk of aortic stenosis (hazard ratio, 0.77 [95% CI, 0.63-0.94]) and a 27% lower risk of aortic stenosis with subsequent complications (hazard ratio, 0.73 [95% CI, 0.56-0.95]), compared with participants in the lowest quintile after adjusting for demographics and cardiovascular risk factors.

CONCLUSIONS

In this study, a high intake of vitamin K1-rich foods was associated with a lower incidence of aortic stenosis and a lower risk of aortic stenosis with subsequent complications.

Patient preferences for heart valve disease intervention

BACKGROUND

This study aimed to determine how patients trade-off the benefits and risks of two different types of procedures used to treat heart valve disease (HVD). It also aimed to determine patients' preferences for HVD treatments (predicted uptake) and the relative importance of each treatment attribute.

METHODS

A discrete choice experiment (DCE) was conducted in Australia and Japan with patients who required a heart valve procedure. Patients were stratified into three categories: no prior procedure experience, minimally invasive procedure experience and invasive procedure experience. DCE attributes included risk of mortality; risk of stroke; needing dialysis; needing a new pacemaker; valve durability; independence 1 month after surgery; and out-of-pocket expenses. Participants chose between two hypothetical labelled approaches to therapy ('invasive procedure' and 'minimally invasive procedure'), with a separate opt-out included. A mixed multinomial logit model was used to analyse preferences.

RESULTS

The DCE was completed by 143 Australian and 206 Japanese patients. Both populations demonstrated an overall preference for the minimally invasive procedure over the invasive procedure. All attributes tested significantly predicted choice and were important to patient decision-making. However, patients' choices were most influenced by the durability of the valve and the likelihood of independence postprocedure, irrespective of their prior procedure experience. Differences in preference were observed between Australian and Japanese patients; valve durability was the most important attribute among Australian patients, while Japanese patients emphasised regaining independence postsurgery. Risk of mortality was less important relative to other key attributes in Japan; however, it remained significant to the model.

CONCLUSIONS

HVD patients prefer a minimally invasive procedure over an invasive procedure, irrespective of prior treatment experience. Key attributes contributing to treatment preferences are valve durability and faster recovery. These results can be used to help inform healthcare decision-makers about what features of heart valve procedures patients value most.

PATIENT AND PUBLIC CONTRIBUTION

People with lived experience of HVD were included in multiple stages of the design phase of this research. First, patients and doctors were consulted by taking part in qualitative interviews. The qualitative interviews helped inform which treatment attributes to include in the DCE based on what was important to those with lived experience and those who help make treatment decisions on behalf of patients. Qualitative interview participants also assisted with the framing of questions in the online survey to ensure the terminology was patient-friendly and relevant to those with lived experience. Following qualitative interviews, the DCE attribute list was agreed on in expert consultation with a steering committee, which included patient representatives and treating physicians (interventional cardiologists, cardiothoracic surgeons). The survey was also pilot tested with a small sample of patients and minor adjustments were made to the wording to ensure it was appropriate and meaningful to those with lived experience of HVD.

Comorbidities and Symptom Status in Moderate and Severe Aortic Stenosis: A Multicenter Clinical Cohort Study

Background

Symptoms associated with severe aortic stenosis (AS) are used to guide management.

Objectives

The purpose of this study was to examine the pattern of symptoms, comorbidities, and cardiac damage in moderate and severe AS.

Methods

A total of 846,198 echocardiographic investigations from 330,940 individuals aged >18 years were selected for the most recent echocardiogram, moderate or severe AS (mean gradient 20.0-39.9 mm Hg, aortic valve peak gradient 3.0-3.9 m/s and aortic valve area >1.0 cm2; or ≥ 40.0 mm Hg, ≥4.0 m/s or ≤1.0 cm2, respectively), and a cardiologist consultation. Natural Language Processing was applied to letters to extract comorbidities, dyspnea, chest pain, and syncope. Patients with prior aortic valve replacement were excluded.

Results

2,213 patients (0.7% overall, 32.8% females) had moderate and 3,416 (1.0%, 47.3% females) had severe AS. Comorbidities were common, including hypertension, (56.6% moderate AS, 53.1% severe AS, P = 0.01), coronary disease (46.0% and 46.8%, respectively, P = 0.58) and atrial fibrillation (29.6% and 34.8%, respectively, P < 0.001). Symptoms were also common in both moderate (n = 915, 41.3%) and severe (n = 1,630, 47.7%) AS (P < 0.001). Comorbidities were more likely in symptomatic vs asymptomatic patients (P < 0.001). Dyspnea was more likely in severe AS, whereas angina and syncope were similar in moderate vs severe AS. In multivariable analysis, only dyspnea was associated with severe (vs moderate) AS (OR: 1.73, 95% CI: 1.41-2.13, P < 0.001). In both adjusted and unadjusted models, the degree of cardiac damage did not relate to presence of any symptoms but was associated with AS severity.

Conclusions

Dyspnea is common in both moderate and severe AS, is associated with comorbidities and is not related to the degree of cardiac damage. Symptom-guided management decisions in AS may need revision.

Wearable Activity Trackers Objectively Measure Incidental Physical Activity in Older Adults Undergoing Aortic Valve Replacement

BACKGROUND

For older adults with severe aortic stenosis (AS) undergoing aortic valve replacement (AVR), recovery of physical function is important, yet few studies objectively measure it in real-world environments. This exploratory study explored the acceptability and feasibility of using wearable trackers to measure incidental physical activity (PA) in AS patients before and after AVR.

METHODS

Fifteen adults with severe AS wore an activity tracker at baseline, and ten at one month follow-up. Functional capacity (six-minute walk test, 6MWT) and HRQoL (SF 12) were also assessed.

RESULTS

At baseline, AS participants (n = 15, 53.3% female, mean age 82.3 ± 7.0 years) wore the tracker for four consecutive days more than 85% of the total prescribed time, this improved at follow-up. Before AVR, participants demonstrated a wide range of incidental PA (step count median 3437 per day), and functional capacity (6MWT median 272 m). Post-AVR, participants with the lowest incidental PA, functional capacity, and HRQoL at baseline had the greatest improvements within each measure; however, improvements in one measure did not translate to improvements in another.

CONCLUSION

The majority of older AS participants wore the activity trackers for the required time period before and after AVR, and the data attained were useful for understanding AS patients' physical function.

Prospective observational study on the accuracy of predictors of high-grade atrioventricular conduction block after transcatheter aortic valve implantation (CONDUCT-TAVI): study protocol, background and significance

INTRODUCTION

Aortic stenosis is the most common cardiac valve pathology worldwide and has a mortality rate of over 50% at 5 years if left untreated. Transcatheter aortic valve implantation (TAVI) is a minimally invasive and highly effective alternative treatment option to open-heart surgery. High-grade atrioventricular conduction block (HGAVB) is one of the most common complications after TAVI and requires a permanent pacemaker. Due to this, patients are typically monitored for 48 hours post TAVI, however up to 40% of HGAVB may delayed, and occur after discharge. Delayed HGAVB can cause syncope or sudden unexplained cardiac death in a vulnerable population, and no accurate methods currently exist to identify patients at risk.

METHODS AND ANALYSIS

The prospective observational study on the accuracy of predictors of high-grade atrioventricular conduction block after transcatheter aortic valve implantation (CONDUCT-TAVI) trial is an Australian-led, multicentre, prospective observational study, aiming to improve the prediction of HGAVB, after TAVI. The primary objective of the trial is to assess whether published and novel invasive electrophysiology predictors performed immediately before and after TAVI can help predict HGAVB after TAVI. The secondary objective aims to further evaluate the accuracy of previously published predictors of HGAVB after TAVI, including CT measurements, 12-lead ECG, valve characteristics, percentage oversizing and implantation depth. Follow-up will be for 2 years, and detailed continuous heart rhythm monitoring will be obtained by inserting an implantable loop recorder in all participants.

ETHICS AND DISSEMINATION

Ethics approval has been obtained for the two participating centres. Results of the study will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ACTRN12621001700820.

Risk for Mortality with Increasingly Severe Aortic Stenosis: An International Cohort Study

BACKGROUND

Aortic stenosis (AS) is the most common valvular heart disease in high-income countries. Adjusted for clinical confounders, the risk associated with increasing AS severity across the spectrum of AS severity remains uncertain.

METHODS

The authors conducted an international, multicenter, parallel-cohort study of 217,599 Australian (mean age, 76.0 ± 7.3 years; 49.3% women) and 30,865 US (mean age, 77.4 ± 7.3 years; 52.2% women) patients aged ≥65 years who underwent echocardiography. Patients with previous aortic valve replacement were excluded. The risk of increasing AS severity, quantified by peak aortic velocity (Vmax), was assessed through linkage to 97,576 and 14,481 all-cause deaths in Australia and the United States, respectively.

RESULTS

The distribution of AS severity (mean Vmax, 1.7 ± 0.7 m/sec) was similar in both cohorts. Compared with those with Vmax of 1.0 to 1.49 m/sec, those with Vmax of 2.50 to 2.99 m/sec (US cohort) or Vmax of 3.0 to 3.49 m/sec (Australian cohort) had a 1.5-fold increase in mortality risk within 10 years, adjusting for age, sex, presence of left heart disease, and left ventricular ejection fraction. Overall, the adjusted risk for mortality plateaued (1.75- to 2.25-fold increased risk) above a Vmax of 3.5 m/sec. This pattern of mortality persisted despite adjustment for a comprehensive list of comorbidities and treatments within the US cohort.

CONCLUSIONS

Within large, parallel patient cohorts managed in different health systems, similar patterns of mortality linked to increasingly severe AS were observed. These findings support ongoing clinical trials of aortic valve replacement in patients with nonsevere AS and suggest the need to develop and apply more proactive surveillance strategies in this high-risk population.

The Role of Transcatheter Aortic Valve Replacement in Asymptomatic Aortic Stenosis: A Feasibility Analysis

Surgical aortic valve replacement (SAVR) is the current treatment of choice for good surgical candidates with moderate to severe symptomatic aortic stenosis (AS). As transcatheter aortic valvular replacement (TAVR) has shown an improved one and two-year all-cause mortality, it has been chosen for moderately symptomatic severe AS patients. The purpose of this review was to perform a clinical comparison of TAVR vs. SAVR and to analyze the Health Index Factor (HIF) that makes TAVR a treatment of choice in asymptomatic AS patients. 

An extensive literature search of PubMed, Cochrane, and Embase databases was performed using the keywords “Aortic stenosis”, “SAVR”, “TAVR”, and “Asymptomatic”. A total of 45 prospective randomized clinical trials in the English language that were published from the year 2000 onwards were included in the final analysis. It has been found that 59.3% of asymptomatic AS patients are likely to die in the next five years without proactive treatment. Multiple studies have proven that early intervention with aortic valve replacement is superior to conservative treatment in severe asymptomatic AS; however, the choice between SAVR and TAVR is not well established. The NOTION Trial, SURTAVI Trail, and PARTNER 3 study have shown the non-inferiority of TAVR over SAVR, during one-year follow-up for low surgical risk patients. Evolut Low-Risk study and Early TAVR are the only two prospective studies performed to date that have enrolled patients with asymptomatic severe AS. The Evolut Trial demonstrated no difference in all-cause mortality at 30 days (1.3% vs. 4.8%. p=0.23), and 12 days (1.3% vs. 6.5%, p=0.11). Additionally, TAVR also decreases the risk of post-procedural atrial fibrillation, acute kidney injury (AKI), and rehospitalization, and leads to significant improvement in the mean trans-aortic pressure gradient. TAVR also showed marked improvement in the 30-day Quality of Life (QOL) index, where SAVR did not report any significant change in the QOL index. However, the official recommendations of Early TAVR are still awaited. TAVR has consistently shown a statistically non-significant difference in case mortality, risk of stroke, and rehospitalization with moderate to high surgical risk patients whereby recent initial trials have shown significant improvement in the QOL index and hemodynamic index for patients with asymptomatic disease. More extensive studies are required to prove the risk stratifications, long-term outcomes, and clinical characteristics that would make TAVR a preferred intervention in asymptomatic patients.

Increasing risk of mortality across the spectrum of aortic stenosis is independent of comorbidity & treatment: An international, parallel cohort study of 248,464 patients

Background

While large scientific and medical evidence has demonstrated the increased risk of death and cardiovascular mortality in patients with severe AS, the independent contribution of moderate AS to an increased risk of death remains uncertain.

Methods and findings

We conducted a multicenter study including a cohort of 30,865 US patients and another cohort of 217,599 Australian patients with equivalent echocardiographic and aortic valve profiling over the same period (2003–2017). During a median 5.2 years (US) and 4.4 years (Australian) follow-up, the risk of death (hazard ratio) of patients with moderate AS as compared to those without AS was 1.66 (95%CI 1.52–1.80) and 1.37 (95%CI 1.34–1.41) in the US and Australian cohorts, even after adjusting this analysis for age and sex. This increased risk of death and cardiovascular mortality (odds ratio) in patients with moderate AS was consistent also across subgroups of left ventricular ejection fraction (LVEF) (subgroups of LVEF < 40%, 40–49%, 50–59%, and ≥ 60%: OR of moderate AS for CV mortality 2.0 [95%CI 1.4–2.7], 1.7 [95%CI 1.2–2.4], 1.5 [95%CI 1.1–1.9], and 1.4 [95%CI 1.2–1.6], respectively).

Conclusions

The findings of this study suggest that patients with moderate AS have a potential increased risk of death and cardiovascular mortality, regardless of age, sex, and LVEF. Hence, these data suggest the need to develop specific strategies to detect and treat individuals with moderate AS.

Uncovering the treatable burden of severe aortic stenosis in the UK

OBJECTIVE

To estimate the population prevalence and treatable burden of severe aortic stenosis (AS) in the UK.

METHODS

We adapted a contemporary model of the population profile of symptomatic and asymptomatic severe AS in Europe and North America to estimate the number of people aged ≥55 years in the UK who might benefit from surgical aortic valve replacement (SAVR) or transcatheter aortic valve implantation (TAVI).

RESULTS

With a point prevalence of 1.48%, we estimate that 291 448 men and women aged ≥55 years in the UK had severe AS in 2019. Of these, 68.3% (199 059, 95% CI 1 77 201 to 221 355 people) would have been symptomatic and, therefore, more readily treated according to their surgical risk profile; the remaining 31.7% of cases (92 389, 95% CI 70 093 to 144 247) being asymptomatic. Based on historical patterns of intervention, 58.4% (116 251, 95% CI 106 895 to 1 25 606) of the 199 059 symptomatic cases would qualify for SAVR, with 7208 (95% CI 7091 to 7234) being assessed as being in a high, preoperative surgical risk category. Among the remaining 41.6% (82 809, 95% CI 73 453 to 92 164) of cases potentially unsuitable for SAVR, an estimated 61.7% (51 093, 95% CI 34 780 to 67 655) might be suitable for TAVI. We estimate that 172 859 out of 291 448 prevalent cases of severe AS (59.3%) will subsequently die within 5 years without proactive management.

CONCLUSIONS

These data suggest a high burden of severe AS in the UK requiring surgical or transcatheter intervention that challenges the ongoing capacity of the National Health Service to meet the needs of those affected.

Incident aortic stenosis in 49 449 men and 42 229 women investigated with routine echocardiography

OBJECTIVE

We addressed the paucity of data describing the characteristics and consequences of incident aortic stenosis (AS).

METHODS

Adults undergoing echocardiography with a native aortic valve (AV) and no AS were studied. Subsequent age-specific and sex-specific incidence of AS were derived from echocardiograms conducted a median of 2.8 years apart. Progressive AV dysfunction and individually linked mortality were examined per AS category.

RESULTS

49 449 men (53.9%, 60.9±15.8 years) and 42 229 women (61.6±16.9 years) with no initial evidence of AS were identified. Subsequently, 6293 (6.9%) developed AS-comprising 5170 (5.6%), 636 (0.7%), 339 (0.4%) and 148 (0.2%) cases of mild, moderate, severe low-gradient and severe high-gradient AS, respectively. Age-adjusted incidence rates of all grades of AS were 17.5 cases per 1000 men/annum and 18.7 cases per 1000 women/annum: rising from ~5 to ~40 cases per 1000/annum in those aged <30 years vs >80 years. Median peak AV velocity increased by +0.57 (+0.36 to +0.80) m/s in mild AS compared with +2.75 (+2.40 to +3.19) m/s in severe high-gradient AS cases between first and last echocardiograms. During subsequent median 7.7 years follow-up, 24 577 of 91 678 cases (26.8%) died. Compared with no AS, the adjusted risk of all-cause mortality was 1.42-fold higher in mild AS, 1.92-fold higher in moderate AS, 1.95-fold higher in severe low-gradient AS and 2.27-fold higher in severe, high-gradient AS cases (all p<0.001).

CONCLUSIONS

New onset AS is a common finding among older patients followed up with echocardiography. Any grade of AS is associated with higher mortality, reinforcing the need for proactive vigilance.