Clinical Outcomes of Patients with ST Elevated Myocardial infarction (STEMI) based on Mode of Transportation to Tertiary Healthcare Facility
Private transport vs. Ambulance services. A study by Scherer, Russ, Jenkins et al. (2012) evaluated the effect of private transport vs. ambulance services on the clinical outcomes of 198 STEMI patients. The median age of the patients was 60 years, and 70% (or 138) arrived at the hospital by private transport of some type, while 30% (or 60) arrived by ambulance services. According to Scherer et al. (2012), "Although not statistically significant due to the great variability in time of arrival for STEMI patients transported by private vehicle, [ambulance] transports had shorter door-to-balloon times" (p. 227). These shorter door-to-balloon times were especially pronounced during business hours and weekend/evenings shifts (Scherer et al., 2012). The findings from this study underscored the need for public awareness campaigns concerning the use of emergency medical services vs. private transport when a heart attack is even suspected. According to Scherer and his colleagues, "Privately insured patients were less likely to use ambulances when experiencing a STEMI. More effective ways are needed to educate the public on the importance of emergency medical services activation when one is concerned for acute coronary syndrome" (p. 230).
In some cases, there may be other ambulance services available, including water-based or air-based services. For example, in Denmark, ambulance services are available but helicopter ambulance services are also routinely used to transport STEMI victims to hospitals (Knudsen, Stengaard, Hansen, Lassen, & Terkelsen, 2012). Both approaches require a significant amount of time, though, with helicopter transport being recommended for patients who lived more than 150 kilometers from a hospital where these services are available (Knudsen et al., 2012).
Although the prevalence of emergency medical services varies significantly in developing nations, some indication of the effect of private transport vs. ambulance services can be discerned from the findings by Park, Kang and Song (2012) that identified across-the-board improved clinical outcomes for STEMI patients arriving by ambulance. According to these clinicians, "Despite recent successful efforts to shorten the door-to-balloon time in patients with acute ST-segment elevation myocardial infarction (STEMI), prehospital delay remains unaffected. Nonetheless, the factors associated with prehospital delay have not been clearly identified in [South] Korea" (p. 864). To fill this gap, Park and her associates retrospectively evaluated 423 STEMI patients and found the median symptom onset-to-door time was 150 minutes, with patients in the short delay group experiencing significantly reduced in-hospital mortality compared their counterparts who experienced long delays in receiving treatment (Park et al., 2012).
Although other causes of delays were also involved, private transport was among the factors that characterized many of those who were placed in the long delay group (Park et al., 2012). In this regard, Park and her associates note that, "Among sociodemographic and clinical variables, diabetes, low educational level, triage via other hospital, use of private transport and night time onset were more prevalent in long delay group" (2012, p. 865). Based on their findings, Park et al. (2012) add that, "Low educational level, symptom onset during night time, triage via other hospital, and private transport were significantly associated with prehospital delay" (p. 864).
These findings also underscore the need to educate the public concerning the symptoms that require immediate medical attention, and the need to use emergency medical responders, including ambulances services, whenever possible. In this regard, Park and her associates conclude that, "Prehospital delay is more frequent in patients with low educational level, symptom onset during night time, triage via other hospitals, and private transport, and is associated with higher inhospital mortality" (p. 869). These findings also emphasize the need to accurately identify the onset of STEMI symptoms and these issues are discussed further below.
Symptom Onset to Arrival in the Emergency Department
Symptom onset of STEMI episodes can result in death immediately, with no time for transport to a tertiary healthcare facility (Evans & Tippins, 2007). In fact, fully one-third of males and a quarter of females die instantaneously from an STEMI onset, while half of all patients experiencing a STEMI episode will die within 30 days of the event, with those who survive beyond that point typically developing differing levels of heart failure over time (Evans & Tippins, 2007).
In these circumstances, timely and efficacious diagnosis and treatment is required to mitigate the effects of the onset of the STEMI episode. The initial diagnosis of STEMI episodes includes the following:
1. History of chest pain/discomfort lasting for 10-20 minutes or more (unresponsive to nitroglycerin);
2. ECG -- persistent ST-segment elevation;
3. Elevated markers of myocardial necrosis; and
4. 2D-echocardiograph (Banerjee, 2011).
With respect to preferred treatments, Ornato (2007) emphasizes that, "The benefit of expertly performed, timely, primary percutaneous coronary intervention (PCI) over fibrinolysis is clear for patients with ST-segment -- elevation myocardial infarction (STEMI)" (p. 6). The timely administration of primary PCI has been shown to be superior compared to fibrinolysis in reducing the of overall short-term mortality, nonfatal reinfarction, stroke, and combined end point of death rates for STEMI patients as well as the nonfatal reinfarction, and stroke rates as well (Ornato, 2007). Interestingly, Ornato (2007) also found that, "These results remain valid during long-term follow-up and are independent of both the type of fibrinolytic used and whether the patient is transferred for primary PCI" (p. 9). Likewise, for those patients who experience ST-elevation myocardial infarctions, there is a growing body of evidence that primary percutaneous coronary intervention (PPCI) is preferable to onsite fibrinolytic therapy (O-FT), when the PPCI is administered in a timely fashion; however, the benefit of this intervention diminishes as delays to treatment increase (Chakrabarti, Gibson & Pinto, 2012), and these issues are discussed further below.
Triage in the Emergency Department
Arrival time to ECG. Although there has been some progress made in improving the performance of tertiary healthcare facilities in responding to the need to use evidence-based quality measures for acute myocardial infarction (AMI), there remains a need for improvement in a key publicly reported quality indicator for AMI (Webster, Curry & Berg, 2007). The AMI is the so-called "door-to-balloon time," which is described by Webster and his associates as "the period from patient (with ST-segment elevation myocardial infarction or STEMI) arrival to provision of percutaneous coronary intervention or balloon angioplasty" (2007, p. 170).
The results of a study by Ornato (2007) also support the need for reduced delays in transport of STEMI patients to hospital facilities. According to Ornato, "Adjusted for patient characteristics, patients with a door-to-balloon time interval >90 minutes were more likely to die compared with patients who had a door-to-balloon time interval ?90 minutes" (p. 6). The findings by Ornato (2007) are also congruent with the guidance provided by the American College of Cardiology/American Heart Association (ACC/AHA) for the management of patients with STEMI. In this regard, Ornato concludes that, "These findings provide evidence-based support for the goal of a door-to-balloon time interval within 90 minutes cited in the and serve as a foundation for the ACC's Guidelines Applied in Practice Door-to-Balloon (GAP-D2B) campaign goal of a door-to-balloon time interval of ?90 minutes in 75% of PCI-treated STEMI patients at participating hospitals nationwide" (p. 9).
The research to date has also identified those aspects of hospitals that have achieved the recommended door-to-balloon times for patients with STEMI on a regular basis, but only in some Western nations (Webster et al., 2008). The initial diagnosis and subsequent treatment of AMI are presently based on the STEMI patient satisfying at least two of the three possible initial diagnostic criteria as follows:
1. A physical presentation demonstrating the clinical signs of ischaemic heart disease.
2. Electrocardiogram (ECG) changes synonymous with the identification of a new left bundle branch block (LBBB); STEMI (this includes S-T segment elevation in ECG leads that would normally view a positive electric…