Enhancing outcomes in acute type A aortic dissection through early diagnosis and access to specialist surgical care

Acute aortic syndrome encompasses a group of life-threatening conditions including aortic dissection; intramural haematoma; and penetrating atherosclerotic ulcer. Type A aortic dissection is the most common aortic emergency with an annual incidence of approximately seven deaths per 100,000 population in the UK [1]. Acute aortic dissection represents a time-sensitive cardiovascular emergency with a high mortality rate if not diagnosed and treated promptly [2]. The Healthcare Services Safety Investigation Body conducted an investigation prompted by the death following an aortic dissection of a 54-year-old patient where there were significant delays in diagnosis and transfer to a specialist centre. The wider investigation initiated by this sad event found that around 20% of patients with acute aortic dissection die before reaching any hospital and 50% die before reaching a specialist centre [3]. Surgical intervention rates for type A aortic dissection have increased significantly in England with a trend to reduced mortality despite an increase in complexity of operations [4]. Retrospective cohort studies have shown consistently a volume/outcome relationship between surgeons and centres; patients operated in high-volume specialist centres have improved survival and lower incidence of complications [4, 5]. The results of the Association for Cardiothoracic Anaesthesia and Critical Care (ACTACC) national audit on the time-critical diagnoses and transfer of patients with acute type A aortic dissection were published recently and highlighted significant gaps in diagnostic processes and quality of transfer [6]. The audit provided a detailed examination of the current state of acute type A aortic dissection management in the UK. Utilising the network of ACTACC link persons, data from 334 patients were reported by 28 UK centres over a period of 1 year. Despite a significant increase in the number of surgical procedures for acute aortic dissection in the UK, substantial delays in diagnosis and transfer to specialist surgical care persist, contributing to patient mortality. The authors defined ‘avoidable delay’ as an interval > 60 min between arrival in the emergency department and onset of surgery. Alarmingly, nearly half of patients (47.3%) experienced such delays. Diagnostic delays were the primary cause in a quarter of these cases and 15.6% of these were linked to misdiagnosis. The symptoms of acute aortic dissection can mimic other conditions such as acute coronary syndrome or pulmonary embolism, leading to diagnostic challenges. However, there are numerous initiatives which are poised to improve diagnostic accuracy significantly. First, awareness of aortic dissection is crucial for early diagnosis. The ‘Think Aorta’ campaign has played a pivotal role in raising awareness. Building on its success will require sustained and widespread training initiatives. Regular education and training for emergency department staff and diagnostic teams are also imperative to improve early recognition of acute aortic dissection. A survey of current policy on recognition and management of acute aortic syndromes in Great Britain found that, of the 111 acute Trusts who responded, only half had specific teaching directed to acute aortic dissection in the emergency department [7]. The Aortic Dissection Charitable Trust website contains excellent medical education material that places the question ‘could it be aortic dissection?’ into the minds of clinicians [8]. Risk scoring tools, such as the Aortic Dissection Detection Risk Score (ADD-RS) and the Aorta Simplified score (AORTAs), can help clinicians identify patients at high risk [9]. Even though there is no specific biomarker that rules out aortic dissection, D-dimer, in combination with clinical risk scores, can aid risk stratification in the emergency department setting. While it is not specific, it has high sensitivity for aortic dissection; the combination of ADD-RS and D-dimer has been well-validated for excluding aortic dissection in patients who are low risk [9]. The AORTAs score plus D-dimer measurement may offer superior specificity while maintaining sensitivity. However, the AORTAs score requires further validation [10]. Table 1 summarises the diagnostic performance of clinical risk scores on their own and in combination with D-dimer. High-risk conditions (e.g. Marfan syndrome, family history) High-risk pain features Physical examination findings ADD-RS plus D-dimer Hypotension, pulse deficits, aneurysm presence, severe pain and neurological deficit AORTAs plus D-dimer ADD-RS > 0: 94.6% ADD-RS > 1: 43.4% ADD-RS plus D-dimer: 93.1–99.8% AORTAs: 92–97% AORTAs plus D-dimer 98–99% ADD-RS > 0: 34.7% ADD-RS > 1: 89.3% ADD-RS plus D-dimer 21.8–67.1% AORTAs: 4–65% AORTAs plus D-dimer: 50–70% The Canadian Clinical Practice Guideline for the diagnosis of acute aortic syndrome helps emergency department clinicians to risk stratify patients presenting with complaints that may be acute aortic syndrome [11]. The RIPP score developed as part of the guidelines evaluates risk using four main categories: risk factors; high-risk pain features; possibility of an alternative diagnosis; and physical examination findings [12]. Patients with a high pretest probability, and those with moderate probability plus an elevated D-dimer, require an urgent CT aortogram [11, 12]. Clinicians face the challenge that acute aortic syndromes are conditions with a relatively low incidence that often present with vague symptoms. A missed or delayed diagnosis can have catastrophic consequences. The ideal biomarker needs to be specific for vascular injury and display high sensitivity and specificity. Cell-free DNA is released due to tissue damage during aortic dissection and is emerging as a promising biomarker [13]. In any case, if diagnostic uncertainty persists, a senior clinician needs to urgently consider information from history, clinical examination and investigations, and perform a CT aortogram if acute aortic syndrome is suspected. Point-of-care ultrasound (POCUS) allows for rapid bedside imaging of the heart, great vessels and abdominal aorta. While POCUS cannot reliably visualise a dissected aorta, it has value as an adjunct diagnostic tool. However, the diagnostic performance of POCUS is insufficiently accurate to allow for recommendation as a stand-alone rule out imaging modality. Reported sensitivity ranges from 41% to 91% and specificity from 94% to 100%, depending on diagnostic criteria for aortic pathology used [14]. Although insufficient as a stand-alone imaging modality, POCUS can raise suspicion of life-threatening aortic pathology by detecting signs such as aortic dilatation, pericardial effusion or aortic regurgitation and prompt definitive diagnosis with a CT aortogram. Recognising the potential of this modality, the Aortic Dissection Charitable Trust offers online educational modules on POCUS in aortic dissection [15]. A CT aortogram is the imaging modality of choice in terms of diagnostic accuracy and anatomical discrimination for acute aortic syndromes. When available, ECG-gated CT aortograms are preferable as gating reduces motion artefacts thereby improving image quality and diagnostic performance [16]. Joint UK practice guidelines from the Royal College of Emergency Medicine and Royal College of Radiology emphasise that CT aortogram provision must be available 24/7 in emergency departments. Clear local protocols and pathways should also detail actions to be taken once acute aortic dissection is diagnosed [17]. Another recent national survey evaluating aortic dissection pathways found a median time to imaging diagnosis of 3.2 h [18]. Once performed, the CT aortogram must be interpreted rapidly and reported by a clinician with experience in aortic imaging. If aortic dissection is diagnosed, the images must be transferred immediately to the appropriate specialist centre. We would welcome more specific recommendations, similar to published trauma guidelines, in terms of recommended reporting times for CT aortograms in acute aortic syndromes. The NHS Acute Aortic Dissection Toolkit, produced by NHS England and NHS Improvement in conjunction with the Aortic Dissection Charitable Trust [19], outlines seven key principles that aim to improve care and survival for patients with acute aortic dissection: regional governance; co-ordination through a regional multidisciplinary teams; a regional rota and single point of contact; timely and reliable image transfer; safe patient transfer; specialist treatment; and a regional education programme [19]. The implementation of such key principles can standardise care and may improve outcomes for patients. Recent joint guidelines from the European Association for Cardiothoracic Surgery (EACTS) and the Society of Thoracic Surgeons on the diagnosis and management of acute aortic syndromes have, for the first time, recognised the aorta as an organ “in its own right” [20]. These guidelines offer comprehensive recommendations for managing aortic disease and emphasise the importance of dedicated aortic teams. Such teams comprise a diverse range of expert specialists who provide 24/7 comprehensive care for both acute and chronic aortic conditions, utilising surgical and endovascular interventions as appropriate. To improve outcomes for patients with acute aortic dissection, it is crucial to enhance timely access to these aortic teams, streamline communication of essential clinical information and imaging, and ensure robust critical care transfer services. The ACTACC audit highlights deficiencies in transfer logistics, with many patients facing delays due to unavailability of ambulances or inefficiencies in the referral process [5]. In 6.9% of cases, patients were refused by the first cardiac centre they were referred to due to capacity issues or lack of expertise. Transfer issues were also identified as a national issue in a report produced by the Health Services Safety Investigations Body [21]. This situation demands the establishment of regional governance structures and standardised emergency referral pathways as outlined in the aortic dissection toolkit. A 24/7 single point of contact for acute aortic syndrome cases in every region could streamline the referral and transfer process, ensuring patients receive timely care. The implementation of the NHS Aortic Dissection Toolkit has facilitated the development of regional aortic networks and the establishment of emergency aortic rotas [22]. The aortic centres within these networks often operate within cardiothoracic units that also house heart attack centres. This overlap presents a unique opportunity to develop a hub-and-spoke model for aortic dissection services in every region, streamlining care and enhancing accessibility. Resolving the issue of patients being turned away from some cardiac centres will require that every region establishes an emergency aortic dissection rota with dedicated aortic centres. Another critical issue highlighted in the ACTACC audit was inadequate medical supervision during transfer [6]. A significant proportion of patients (85%) were transferred without a doctor, and 17% deteriorated on route to the cardiac centre. Careful monitoring and management of haemodynamics, including infusions of anti-impulse drugs such as labetalol, is essential to prevent deterioration. Intravenous beta-blockers rather than pure intravenous vasodilators for control of blood pressure are effective in reducing the force of cardiac contractions, lowering blood pressure and reducing aortic wall stress [23]. An analysis of the International Registry of Acute Aortic Dissection database found that intravenous beta-blocker therapy was associated with improved outcomes in patients with acute type A aortic dissection [23]. A systolic blood pressure target of 100–120 mmHg and a heart rate of 60–80 bpm are the recommended therapy targets. An expert specialist group produced a consensus statement setting out logistical recommendations for the safe and expeditious transfer of patients with acute aortic syndrome to specialist centres [16]. The consensus guides implementation of the principles delineated in the NHS Aortic Dissection Toolkit. NHS England recently published a service specification document for its centrally commissioned adult critical care transfer services mandating their involvement in the transfer of patients with acute aortic dissection [24]. Critical care transfer services are regionally based which allows them to adapt to challenges specific to their geography and population, and to develop close governance links with their respective aortic centres. Despite recent advances, significant barriers remain with 24/7 critical care transfer services not yet available universally in all regions. The presence of a specialist transfer team, including medical personnel trained to manage haemodynamic and neurological instability, is essential to ensure that adequate therapy is administered during transfer and that vital signs targets are achieved consistently. Timely diagnosis and transfer to specialist centres will not only improve survival but also allow for optimisation of peri-operative care potentially leading to a reduction in complications. Early recognition and transfer increase the likelihood of the patient arriving to the specialist centre without irreversible organ dysfunction. Improvement in survival rates and reduction of complications for patients presenting with type A aortic dissection is achievable but relies on the patient receiving specialist surgical treatment as soon as possible. Prompt specialist surgical treatment is only possible if the condition is suspected and diagnosed, and the patient is safely transferred to the surgical centre in a timely fashion. We appreciate deeply the vital contributions of patient advocacy groups and aortic dissection charities, who are continuous drivers for progress and foster innovation in the care of patients with aortic dissection. The ACTACC audit provides a comprehensive assessment of the current state of type A aortic dissection management in the UK, revealing critical areas for improvement [6]. By addressing diagnostic delays, enhancing transfer logistics, ensuring appropriate medical supervision during transfers and implementing standardised referral pathways, we can significantly improve outcomes for patients with aortic dissection. This audit serves as a call to action for healthcare professionals and policymakers to prioritise and implement the necessary changes urgently. No competing interests declared.