Primary percutaneous coronary intervention (PPCI), also known as coronary angioplasty, is considered the therapy of choice for patients experiencing ST-elevation myocardial infarction (STEMI) (Weitsman and Meerkin, 2013). However, when myocardial reperfusion is required or if a delay of ≥60 minutes is inevitable or unavoidable, should PPCI be used as an adjunct to thrombolysis therapy—and could this improve patient outcome and long-term prognosis (Mannsverk et al, 2019)? The present discussion focuses mainly on the UK's NHS ambulance trusts’ response to these patients, and explores some of the reasons for potential delays. Although there are a myriad of reasons for delays, this article will focus on a patient's poor understanding of their circumstances and access to a PPCI treatment centre, as well as some of the social, geographic and demographic conditions (such as an ageing population who are more likely to experience complications) who present to 999 services and treatment centres in a 24-hour health service.
These factors can lead to delays in an ambulance responding to an emergency, transporting a patient, and consequently arriving late to an appropriate facility where the ‘gold standard’ PPCI treatment for a STEMI can be performed (Jordan and Caesar, 2016).
Background and pathophysiology
Benger's (2016) research for the National Institute For Health Research (NIHR) noted that more than 30 000 cardiac arrests occurred outside the hospital in England every year (Benger, 2016; Out of Hospital Cardiac Arrest Steering Group, 2017).
STEMI is an internationally recognised acronym for a heart attack (Thygesen et al, 2012) and a STEMI is ‘a cardiac emergency with a high early mortality’ (Radke, 2011). ST elevation is identified when changes in a patient's electrocardiogram (ECG) are seen (Thygesen et al, 2012).
The scenario can arise when an adult patient in a prehospital setting calls 999 for an ambulance and presents with the signs, symptoms and ECG of someone experiencing a spontaneous onset of myocardial infarction (MI) or having a ‘heart attack’, as described by Leslie et al (2019). A relative or friend may also call for an ambulance.
However, Dr Mikkel Schoos from the University Hospital of Copenhagen in Denmark noted that ‘just 29% of patients went to hospital by ambulance’ (European Society of Cardiology (ESC), 2012).
This could indicate that while there may be delays in dispatching an appropriate ambulance and crew, it could be that a patient does not call for an ambulance for many hours. There are little or no differences in age, sex and/or marital status between those who call for an ambulance and those who do not (ESC, 2012). The data for this study were compiled in Norway and Denmark; it was noted that some patients live >100 km (60 miles) from a hospital with PPCI facilities and these patients normally visit a local hospital first. In the UK, an ambulance on occasions has to travel distances of 50–65 km (31–41 miles).
Other factors may also cause delays, as are highlighted in NHS England's (2017)Ambulance Response Programme. Evaluation of Phase 1 and Phase 2 report.
Mannsverk et al (2019) also noted this within their study, which has similar geographical and urban characteristics to those negotiated by emergency vehicles in the UK. It is not uncommon for the journey from the initial 999 call to arrival at the PPCI facility to take anything from 1 hour and 15 minutes to 2 hours, with an ever-increasing incidence of even longer journey times dependent on road/traffic conditions.
In addition, Mannsverk et al (2019) found that the crew may not have the ability or be appropriately educated enough to transmit an ECG, or be confident enough to make the decision to go past the local hospital.
The NHS England (2017) report also highlighted problems experienced by the UK's 10 NHS ambulance trusts and acknowledged the difficulties they have to deal with because of the aforementioned issues. The Health and Social Care Information Centre (2015) reported:
‘For ambulances, the volume of 999 calls has more than doubled in the last ten years and in 2014/2015 stood at a record high of 9 million calls in England.’
The number of ambulance calls and NHS 111 transfers (when an ambulance is automatically dispatched) increased from 7.9 million from June 2012 to 10.7 million in March 2013—an average year-on-year increase of 5.2% (National Audit Office (NAO), 2017).
Therefore, although ambulance services in the UK are not in the same situation as those discussed by the ESC (2012), when the UK's greater urbanisation and geographic complications are taken into consideration, they can be seen to be in a comparable position. This suggestion is reinforced by Zulfiquar and Belder (2018), and Ezad et al (2018).
An example of how commonplace it is that ambulances have to bypass their local hospitals and go to an appropriate facility was highlighted by a consultant prehospital care practitioner (a paramedic) for the South Central Ambulance Trust (Benger, 2016). The paramedic noted an increase in the stress levels of crew members who had to bypass a local hospital to take a critically injured or unwell patient directly to a specialist centre.
Given the above, it may be in the patient's best interest to delay PPCI by stabilising them first, as highlighted by Mannsverk et al (2019) in a study of prehospital thrombolytic therapy. Although this is not the gold standard treatment, it is effective, especially when performed within 2 hours of first medical contact (Radke, 2011). As noted, a patient can be ≥90 minutes or 2 hours away from a PPCI suite, with the potential for these timings to even exceed this 2-hour window.
On occasions, a patient may present with a STEMI that has been confirmed by an ‘adequately’ educated 999 NHS ambulance crew (ESC, 2012). The crew can then transmit the patient's ECG and, if required, transport the patient to their nearest PPCI centre.
A PPCI facility may allow emergency paramedic crews to transmit a patient's ECG and discuss the patient's symptoms with a cardiac specialist before arrival at the facility. This starts and facilitates the two-way communication required to give the patient the best, most appropriate treatment with an expedient delivery (ESC, 2012; Mannsverk et al, 2019).
Speaking at the Acute Cardiac Care Congress in Istanbul, Turkey, in 2012, Schoos observed and highlighted various complications and treatment pathways in Denmark that are similar to those experienced and used in parts of the UK (ESC, 2012). Of the four health system models described by Isik et al (2015), the one used by the UK—the Beveridge Model—is also used by many other countries including Denmark, Sweden and Norway. A central tenet of this model is that health is a human right so ‘anyone who is a citizen has [a right to] the same access to care’ (Chung, 2017).
Isik et al (2015) said that healthcare is an indicator of a country's socioeconomic development, adding that all countries should be able to provide high-quality, accessible healthcare services and that everyone has the ‘right of healthy life’.
Ultimately, if a patient meets the criteria to be transported, it is important that this is facilitated in the best, most appropriate and expedient manner to the PPCI; the duration of this journey is commonly referred to as door-to-balloon (D2B) time (Roswell et al, 2014).
Radke (2011) notes that ‘direct percutaneous recanalization of the infarct-related artery represents the gold standard in treating STEMI, specifically when performed within 2 hours after first medical contact’ but adds that ‘these timelines imply logistical challenges for ambulance and hospital services’.
Johnson et al (2016) state that calling for an ambulance improves the survival chance of patients who experience an out-of-hospital cardiac arrest. However, their study, along with those by Edwards et al (2019) and Perkins et al (2016) on behalf of the Community Resuscitation Group, highlights that more research needs to be carried out in the UK.
There are various reasons why a patient may attend their local hospital first (ESC, 2012). These include a patient not fully understanding their symptoms or, as mentioned, that the crew attending the patient do not have the ability or have not been trained adequately to transmit an ECG to the specialist centre or may not be confident enough to make a decision to bypass the local hospital (Mannsverk et al, 2019).
Given the potential for delays in reaching a PPCI facility, it could be suggested that it would be most expedient if first-line treatment were stabilisation with thrombolysis (Mannsverk et al, 2019) in cases where transition time is going to be 60 minutes or more, even though the gold standard for treatment of a confirmed STEMI is usually PPCI.
Thrombolysis or thrombolytic therapy is the administration of drugs commonly called clot busters or fibrinolytic therapy, which can dissolve blood clots that have caused arteries or veins to become narrowed or blocked (Rivera-Bou et al, 2017). They are used in a variety of scenarios including STEMI, stroke and embolism.
Methods
A systematic approach was taken to completing an in-depth journal review to ensure that the following question was sufficiently and critical appraised: ‘Would a better outcome be achieved for patients presenting with a STEMI, if PPCI was used as an adjunct to thrombolytic therapy, where a delay of ≥60 minutes is inevitable or unavoidable?’
This involved drawing from a comprehensive range of articles, research materials, studies and search engines to ensure a balanced and in-depth range of sources: BMJ Quality; Google Scholar; Medscape; Nice.org.uk; NHS Improvement; Nih.gov; National Audit Office; National Institute For Health Research;National Audit For Percutaneous Coronary Intervention; PubMed; and Wiley Online Library.
Consideration was also given to the focus of databases. For example, CINAHL is medically focused, which could be deemed to have limitations in the prehospital setting of the question being asked. However, Polit and Beck (2017) recommend its use in healthcare andCreswell (2014)concurs, saying databases are a useful tool to access literature.
Search terms included: ‘MI gold standard’, ‘PPCI for confirmed STEMI’, ‘door to balloon (D2B) best practice’, ‘thrombolysis’, ‘MI anticoagulation therapy’ and ‘delay of PPCI in heart attacks’ (Table 1). Articles included statistic values and techniques dating from 2005 to 2019; restricting the search to this period meant that only up–to-date literature was included.
| ‘MI gold standard’ OR ‘PPCI confirmed STEMI’ OR ‘Door to balloon best practice’ OR ‘Thrombolysis’ OR ‘MI anticoagulation therapy’ |
| AND |
| ‘Pre-hospital’ OR ‘Prehospital’ OR ‘Ambulance’ OR ‘Time delays of ≥60 minutes’ OR ‘Ambulance response times’ OR ‘Delay of PPCI in heart attacks’ |
The primary sources used to address the research question were Mannsverk et al (2019) and research included in the ANZCOR Guideline 14.3—Acute Coronary Syndromes: Reperfusion Strategy from the Australian Resuscitation Council and the New Zealand Committee on Resuscitation (ANZCOR, 2016). These were used because both agree that ‘PPCI is the preferred perfusion strategy with the best outcomes [and] the benefit is mostly driven by reduced rates of recurrent myocardial infarction in the PPCI treated patients compared to those receiving fibrinolysis’ (ANZCOR, 2016). Both also acknowledge that ‘complications’, including geographical locations or demographic considerations, could prevent or hinder the gold standard of treatment.
Discussion
Steg et al (2003) note that ‘longer door-to-balloon times, total duration of ischaemia, and time of presentation relative to symptom onset all have an impact on outcomes following primary percutaneous coronary intervention’. Furthermore, ANZCOR (2016), Schoos (ESC, 2012) and Mannsverk et al (2019) acknowledge this, while also recognising that geographical and demographic considerations need to be taken into account where access to the gold standard is not practically possible.
‘In many parts of Australia and New Zealand, PPCI is not widely available and for PPCI to maintain superiority over fibrinolytic therapy, the PPCI related delay must be between 45 and 180 minutes depending on the patient's condition’
There are many reasons why PPCI is not widely available in many parts of these countries, including large geographical areas and the remoteness of towns, which limit access to PPCI specialist centres. Mannsverk et al (2019) noted that many areas of these countries were accessible only by helicopter and aeroplane services.
Although these geographical conditions do not apply exactly to the UK, it could be argued that these examples provide a useful model to observe the regular practices and outcomes for these patients where there are delays in receiving PPCI or reaching a PPCI centre.
The South East Coast Ambulance Service NHS Foundation Trust's (SECAS) (2018)Account & Quality Report 2017/18 states that all ambulance trusts, as instructed by NHS Improvement, will deliver an ambulance response programme and introduce condition-specific measures. This means that every 999 call to hospital for heart attacks (and strokes) is tracked. With improvements to response times and treatment times being implemented by 2022, ambulance trusts ‘will expect that 90% of eligible heart attack patients [will] receive treatment within 150 minutes’ (SECAS, 2018). However, though the trust had set this target, it was still some way short of the gold standard.
ANZCOR (2016) acknowledges the limitations in trying to provide PPCI in the geographical area it covers but says that the maximum delay that is acceptable from onset or presentation of symptoms to D2B is ‘60 minutes if a patient presents within 1 hour of symptom onset; or 90 minutes if a patient presents later’.
This point is reinforced by Schoos (ESC, 2012), who adds that ‘patients more than 100 km away … could be treated first with clot-dissolving drugs (thrombolysis), followed by balloon treatment when they arrive at the [PPCI] centre’.
Prehospital thrombolytic therapy (PHT) is most effective if given as soon as possible, and is ideally administered within 2 hours of pain onset (Mannsverk et al, 2019). Although journeys of 100 km are rare in the UK, UK ambulances do on occasions have to travel these distances. More importantly, as mentioned by NHS England (2017) and SECAS (2018), problems and difficulties facing the UK's 10 NHS ambulance trusts are increasing.
Long and complex journeys delay responses to emergency calls and this is exacerbated by increasing demand for ambulance services.
This demand is unfortunately predicted to grow rapidly. While ambulance travel distances may not increase, demand may well reduce the ability of the ambulance services and crews to respond in the most expedient manner possible. This will affect the time it takes until patients with STEMI are diagnosed and have their ECG transmitted, as it will take longer for the crew to consult, treat and transport the patient to the most appropriate PPCI specialist hospital.
Mannsverk et al (2019) demonstrate that prehospital reperfusion can mean patients are treated significantly earlier’. However, they acknowledge it took 11 years to upgrade and improve the availability and reliability of a PHT system.
Having ambulance clinicians provide thrombolysis, with the support of GPs and hospital cardiologists, led to ‘significant reduction in post-infarct systolic heart failure and high survival rates in STEMI patients’ (Mannsverk et al, 2019).
For patients with acute coronary syndrome, the Scottish Intercollegiate Guidelines Network (SIGN) (2016) specifies that:
‘prehospital thrombolysis is indicated if the time from the initial call to arrival at hospital is likely to be over 120 minutes’.
This appears to indicate that it would be better to provide thrombolytic therapy initially (within 30 minutes) rather than travelling for a further 30–90 minutes (60–120 minutes in total) to reach a facility that can provide PPCI.
Patients could also be treated by thrombolysis followed by balloon treatment when they arrive at a PPCI centre (ESC, 2012; Mannsverk et al, 2019).
It can also be acceptable to bypass a local hospital with no PPCI facility to attend one that provides this procedure because ‘the majority of patients with acute heart attacks can be safely transported even if these hospitals [with PPCI facilities] are further away than smaller local hospitals’ (ESC, 2012).
Helicopters can be used to transport patients when going by road could delay treatment (ESC, 2012; Mannsverk et al; 2019); this is already done by some UK ambulance trusts.
Further research and implications
While carrying out this study, the author has learned a great deal. This information has and will have a practical effect in the author's treatment of patients presenting with a STEMI, alongside providing a deeper understanding of knowledge.
While it is important to get a patient to one of the UK's 118 PPCI centres as quickly and as safely as possible, if this is not possible, other treatments are available within some pathways. However, these interventions need to be researched further before being introduced into mainstream practice in the UK.
The National Audit For Percutaneous Coronary Intervention, 2019 Summary Report (National Institute for Cardiovascular Outcomes Research (NICOR) and British Cardiovascular Intervention Society (BCIS), 2019) highlights several issues that need to be addressed including: the deterioration in ambulance response times; that only 76.8% of PPCI procedures are performed with a D2B time of <60 minutes; and variation in D2B time between areas.
The report notes that D2B times have increased by 9 minutes since 2015 (NICOR and BCIS, 2019), which could suggest that where PPCI is not easily or readily accessible, other treatments may be more appropriate in the first instance for patients who present with the symptoms of a STEMI.
For the author, practice learning has included the use, duration and administration of oxygen, and the composition, actions and metabolic effects of a medication on a patient. Alongside this, a greater understanding was gained of the analgesic and anticoagulant therapies of various medications including clopidogrel, prasugrel, ticagrelor, cangrelor, and aspirin.
Matters to consider in the UK include demographic changes, geographic boundaries, cultures, populations and lifestyle choices (Cassidy et al, 2017; Donin, 2018). These studies suggest the health service needs to change constantly and research will be needed to investigate and develop the health system model so that needs can be met.
Mannsverk et al (2019) demonstrated significant time gains and earlier reperfusion therapy in a ‘decentralised’ PHT system that was improved and upgraded, maturing over 11 years. As highlighted, PHT was performed by ambulance clinicians with the support of GPs and hospital cardiologists. This may be a pathway that the UK could take in developing an ever-changing and evolving health service.
Conclusion
From formulating the original question—‘would a better outcome be achieved for patients presenting with a STEMI, if PPCI was used as an adjunct to thrombolytic therapy, where a delay of ≥60 minutes is inevitable or unavoidable?’—to carrying out the research, the author discovered a multitude of facts, figures, opinions and conclusions. These had varying hypotheses and, in some cases, predicted outcomes and suggested ideas on what is best.
There was a consensus that the gold standard of care for an adult patient presenting with a confirmed STEMI is PPCI. However, there was less certainty regarding what should happen if a patient with a confirmed STEMI was ≥60 minutes away from an appropriate PPCI centre with enough trained staff available. This issue was recognised by Nikolaou et al (2015) and Mannsverk et al (2019).
On the basis of what the author has learned, it could be suggested that, for a number of reasons including increasing urbanisation, population growth and a reduction in funding for NHS hospitals, patients may not readily be able to access PPCI within 60, 90 or 120 minutes. Given this, further training and funding should be considered for those who handle 999 calls so they can dispatch the best resource.
At this point, the crew would rapidly and safely make their way to the patient, then assess, treat and transmit clinical findings to a specialist cardiologist within the PPCI facility. The crew would then quickly and safely transport the patient to the PPCI unit.
The PPCI suite may be some distance away, so there may be occasions when the ambulance crews could start thrombolysis treatment or stop at a local hospital that could provide it. Both of these options could allow commencement of thrombolysis treatment many tens of minutes before the patient can receive the recommended gold standard treatment at an appropriate facility.