Cardiovascular disease (CVD) is the most common cause of death worldwide.1 With an estimated 7.6 million global deaths due to coronary heart disease in 2005,2 the size of the burden placed on society cannot be understated. Acute myocardial infarction (AMI), the classic ‘heart attack,’ will be the classification given to many of these deaths. In its most life-threatening form, AMI is identified with ST-segment elevation myocardial infarction (STEMI) indicated via 12-lead echocardiography (ECG). Primary percutaneous coronary intervention (PCI) has been shown to demonstrate superior clinical outcomes for patients presenting with STEMI in terms of its ability to achieve higher patency rates, minimize infarct size, and improve left ventricular function and long-term survival (as well as lower rates of reinfarction and stroke compared with thrombolytic therapy).3,4 As a result, more than 500,000 PCI procedures are performed yearly in the US alone,5 and it has been estimated that more than one million procedures are performed annually worldwide.6 However, although primary PCI is highly effective, as with other treatments its efficacy is also time-dependent.
Clinical Evidence
For all forms of PCI in STEMI, there is undisputed agreement that every effort must be made to minimize the interval time between onset of chest pain or other symptoms and the initiation of a safe and effective reperfusion strategy, known as ‘total ischemia time.’ After adjustment for baseline characteristics, time from symptom onset to balloon inflation is significantly correlated with one-year mortality in patients undergoing primary PCI for STEMI. With each 30-minute delay between symptom onset and balloon inflation, risk for patient mortality increases by 7.5%.7 Of particular importance to this discussion is our knowledge that the mortality benefits of primary PCI over thrombolytic therapy are especially dependent on ‘door-to-balloon time’ (defined as the interval between arrival at the hospital and intracoronary balloon inflation). Researchers of an observational study involving 661 community and tertiary care hospitals in the US found that door-to-balloon times significantly increased the adjusted odds of in-hospital mortality (41–62% for patients with door-to-balloon times >120 minutes), whereas mortality did not increase significantly with increasing delay from onset of symptoms to first balloon inflation.8
Similarly, a cohort study of 29,222 STEMI patients treated with PCI within six hours of presentation at 395 US hospitals participating in the National Registry of Myocardial Infarction (NRMI) reported that longer door-to-balloon time was associated with increased in-hospital mortality.9 Adjusted for patient characteristics, patients with door-to-balloon time >90 minutes had increased mortality (odds ratio 1.42; 95% confidence interval [CI] 1.24–1.62) compared with those who had a door-to-balloon time of ≤90 minutes. The authors concluded that time to primary PCI is strongly associated with mortality risk and is important regardless of the time from symptom onset to presentation and of baseline risk for mortality. These and other data support the decision of European and US professional bodies to reduce recommended targets for door-to-balloon times. In 2005 the European Society of Cardiology (ESC) and American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for patients with STEMI were updated to recommend that primary PCI should be performed as quickly as possible, with a target of medical-contact-to-balloon or door-to-balloon times of ≤90 minutes.6,10
Discussion—Meeting the Challenge
Not all of the causes of delay can be influenced within hospital practice. Problems lie within the time taken to recognize symptoms and inform emergency services. More needs to be done with regard to improving patient/public education in order to elicit early emergency calls. Transportation delays require problems to be overcome within the organization of paramedic emergency services. However, the evidence above suggests that it is the time from first medical contact that is most critical. Many patients presenting with STEMI are still not treated within the guideline recommendation. Achieving this level of performance is uncommon across Europe and, in particular, the US, leading the ACC to describe implementation of the 90-minute guideline as “an organizational challenge.”11
In a study sponsored by the National Heart, Lung, and Blood Institute (NHLBI), 365 hospitals were surveyed anonymously to determine the procedures in place to minimize door-to-balloon times.12 Only 35% reported a median door-to-balloon time of ≤90 minutes; 48% had a median door-to-balloon time of 91–120 minutes, 13% of 121–150 minutes, and 4% of >150 minutes. A study author noted that if every hospital met the guidelines, 1,000 lives could be saved each year.
The study authors made recommendations regarding strategies to improve door-to-balloon times. These included emergency department physicians utilizing electrocardiogram (ECG) data taken en route by paramedics to activate the angioplasty team, a single call page operator to activate the catheterization laboratory and the staff to arrive within 20 minutes, and realtime feedback to be used for the angioplasty and emergency teams.
Other studies have shown that the determined implementation of strategies designed to reduce door-to-balloon times can have a significant impact. Staff at Rochester’s Mayo Clinic formed a multidisciplinary team in an effort to bring door-to-balloon time to within the target 90 minutes.13 The most significant changes associated with reducing mean door-to-balloon time to 70 minutes were reported as:
- emergency physician activation of cardiac catheterization team by a group page activation;
- predetermined time-based goals for each step of the patient care process (making a total door-to-balloon time of <90 minutes);
- strong inter-departmental communication between cardiology, emergency medicine, communications, quality, and nursing; and
- prompt feedback of time-based results to staff involved in the care of STEMI patients.
Other researchers have shown various audit-based outcomes, including setting, measuring, and reviewing target times and educating physicians, cardiologists, and nursing staff to be valuable in reducing median door-to-balloon times from 130.5 to 109.5 minutes (p<0.001).14 The qualitative analysis by Bradley et al. of 11 hospitals participating in the NRMI that had demonstrated substantial improvement in terms of shorter door-to-balloon times between 1999 and 2001–2002 identified eight common themes that were consistently associated with improved delay times:15
- setting the explicit goal of reducing door-to-balloon times;
- active, visible senior administrator support;
- innovative protocols, based on creative identification of delays and how to reduce them;
- flexibility in refining standardized protocols;
- driven, highly respected individual clinical leaders who pushed persuasively for improvement;
- collaborative interdisciplinary teams made up of people equally committed to the goal;
- non-blaming data feedback mechanisms for identifying problems and successes and conveying these to team members; and
- an organization “that fosters resilience to challenges or setbacks.”
Furthermore, in a survey of 365 hospitals, hierarchical and generalized linear models and data on patients from the Centers for Medicare and Medicaid Services were used to determine the association between hospital strategies and the door-to-balloon time. Results of the multivariate analysis highlighted six strategies significantly associated with a faster door-to-balloon time. These strategies included having emergency medicine physicians activate the catheterization laboratory (mean reduction in door-to-balloon time 8.2 minutes), having a single call to a central page operator activate the laboratory (13.8 minutes), having the emergency department activate the catheterization laboratory while the patient is en route to the hospital (15.4 minutes), expecting staff to arrive in the catheterization laboratory within 20 minutes of being paged (versus >30 minutes) (19.3 minutes), having an attending cardiologist always on site (14.6 minutes), and having staff in the emergency department and the catheterization laboratory use realtime data feedback (8.6 minutes).12 Despite the effectiveness of these strategies, authors reported that only a minority of US hospitals surveyed were using them. As a consequence, in November 2006 the ACC, together with the AHA and other key national healthcare organisations, announced its D2B (Door-to- Balloon): An Alliance for Quality campaign in an effort to improve door-to-balloon standards.
Industry can also continue to play its role in improving the ways in which it can support a holistic approach to reducing the time to treatment. Technological advances already offer methods of capturing and sending digital-quality 12-lead ECG data to multiple points of contact at the hospital, as well as mobile devices, in order to assist early decision-making processes. These systems allow paramedics to immediately transmit data from the ambulance to the hospital. In turn, clinicians in hospitals can receive ECG data and assess a patient’s condition and the type of treatment they will need before the patient even arrives at the emergency department.
As a patient moves through the cycle of cardiac care, whether in the ambulance, emergency department, diagnostic imaging center, catheterization laboratory, operating room, and/or critical care ward, technology can help to manage the flow of patient information, making it available when and where it is needed to enable health providers to offer better, faster care. Data from this technology in use have demonstrated reliability and shown improved door-to-balloon time in studies.16
There is little left now to do except to get on with implementing change. The way forward seems clear, and the tools and technology to help us are in place. It has been suggested that perhaps the biggest barrier to implementing co-ordinated improvements is the power of inertia. Even though we can identify strategies and judge institutional preparedness, authors have noted that actual improvement requires moving “beyond preparedness to action.”14
Conclusion
The benefits of reducing the time period from discovery to treatment and meeting door-to-balloon guidelines for AMI are known and well documented. The strategies and protocols that will assist clinicians to achieve the targets that have been set are available. Technological advances to improve outcomes are in place and are cost effective. A paradigm shift is now required in order to bring what we know to be best practice and modern technology together in order to improve overall quality of care for patients with STEMI. Healthcare professionals in Europe and the US have an opportunity to work with educators, regulators, and industry to lead a global drive to make rapid discovery to treatment standard practice.