The working group identified four critical time points in the care of these patients and termed them the "four D's." (Fig. 3). "Door" is the time of arrival and registration of the patient in the emergency department. "Data" refers to the time that the first ECG showing ST-segment elevation is recorded, since this electrocardiographic finding is clearly the trigger for consideration of reperfusion therapy. "Decision," the third D, is the time when the decision to proceed with reperfusion therapy is made (the drug is ordered). The fourth D, "Drug," is when the thrombolytic infusion is actually begun. The elapsed time between the patient's emergency department arrival and initiation of thrombolytic drug is then referred to as "door-to-drug time." In the case of patients receiving balloon angioplasty, the interval is referred to as the "door-to-balloon" (26) or "door-to-dilation" time (20). The working group analyzed the process of care in the emergency department, based on the four D's, identifying the potential for delays.
Once the patient arrives in the emergency department, the initial encounter with the nurse or registration representative should be focused on clinical symptoms and not on the collection of demographic information (12). If a patient complains of chest pain, then triage to a high category with an ECG done within 5 min and physician assessment within 10 min should be expected.
While substernal chest pain remains the cornerstone of patient history for acute MI diagnosis, two recent reports from a large series of patients provide rich additional information as to how patients may present. Goldberg et al. (27) reported on the symptom profiles of patients presenting with a complaint of chest pain and a hospital-admission diagnosis of suspected acute myocardial ischemia and a discharge diagnosis of acute MI or unstable angina in 43 hospitals in 20 communities throughout the United States during collection of baseline data for a larger community intervention trial. They noted that four other "cardinal" symptoms of a heart attack or unstable angina—dyspnea (49%), arm pain (46%), sweating (35%), and nausea (33%)—were commonly reported by men and women of all ages in addition to the presenting complaint of chest pain. Patients with acute MI were more likely to complain of arm pain, sweating, nausea, vomiting, and indigestion. Patients with a diagnosis of unstable angina were more likely to complain of neck pain, dizziness, and palpitations (27).
Furthermore, in nearly 435,000 patients with confirmed MI from the National Registry of Myocardial Infarction (NRMI) 2 (enrolled from June 1994 to March 1998), 33% (one in three) did not have chest pain on presentation to the hospital. This group of MI patients was on average 7 yr older than those with chest pain (74.2 vs 66.9%); and a higher proportion of them were women (49 vs 38%) and patients with diabetes mellitus (32.6 vs 25.4%) or prior heart failure (26.4 vs 12.3%). Also, MI patients without chest pain had a longer delay before hospital presentation (mean 7.9 vs 5.3 h), were less likely to be diagnosed as having confirmed MI at the time of admission (22.2 vs 50.3%), and were less likely to have received thrombolysis or primary angioplasty (25.3 vs 74.0%), aspirin (60.4 vs 84.5%), p-blockers (28.0 vs 48.0%), or heparin (53.4 vs 83.2%). MI patients without chest pain had a 23.3% in-hospital mortality rate compared with 9.3% among patients with chest pain (28).
Locating an ECG machine in the emergency department will reduce door-to-data time. Acquisition of the 12-lead ECG should be possible within 5 min, 24 h a day, 7 d a week. If this cannot be accomplished effectively using technical staff, then emergency department personnel, including nurses or physicians, should be trained to acquire a high-quality 12-lead ECG. The nurse should have authority to order the 12-lead ECG, rather than waiting for a physician assessment and order.
Once the ECG is available, it should be delivered to the physician for interpretation rather than placed on the chart or at the nurse's desk. In the Time to Thrombolysis Sub-study of the NRMI, the median door-to-decision times and door-to-drug times were significantly longer when a consultation by a cardiologist was performed, and these times were substantially longer for those patients who had a bedside consultation compared to those whose consultation occurred by phone (29). Fax consultation for the purpose of interpreting the ECG significantly reduces data-to-decision time and, therefore, median door-to-drug time (30). Contacting the primary care physician before initiating thrombolytic therapy substantially delays door-to-drug time (29). Consultation particularly contributes to delays around the decision to treat women with a thrombolytic agent and in initiation of drug therapy (29). In another study, the median time interval from hospital arrival to initiation of thrombolytic therapy was longer in the consultation group (49 vs 35 min, p = 0.0001). A door-to-drug interval of <30 min was seen in only 23.8% of the consultation group vs 40.4% of the no consultation group (31).
Preparation of the drug in the emergency department as opposed to the pharmacy can result in substantial decrease in door-to-drug time with a difference in one study being 61.5 as opposed to 84.6 mean min (30). Furthermore, waiting to initiate drug infusion in the cardiac intensive care unit results in the greatest delay, 75 min, compared to 50 min when the infUsion is begun in the emergency department (30). Extensive written informed consent is not appropriate for a patient with severe chest pain who is suffering an acute MI. The patient may be appropriately informed verbally of benefit and risk within 1 to 2 min by the physician, since reperfusion therapy, like many others in medical emergencies, is now standard of care. There is no evidence that patients who qualify for thrombolytic therapy should be transferred to a tertiary care hospital or center for initiation of drug, since the delay related to transfer will invariably increase mortality. Rural hospitals and community hospitals in urban settings must be capable of treating patients with acute MI with thrombolytic drugs according to the same standards for early diagnosis and treatment as the cardiology centers. Telephone and fax consultation with cardiologists in other hospitals may be appropriate to facilitate care in difficult cases.
Thus, it is imperative that the process of assessing patients with chest pain, acquiring the 12-lead ECG, and making decisions to initiate reperfusion therapy be seamless and consistent. Furthermore, for patients with clear cut clinical symptoms of acute MI and unequivocal evidence of ST elevation on the ECG with no question of contraindications, the responsibility to order and initiate thrombolytic therapy should be delegated by protocol to the emergency medicine physician. Waiting for the cardiologist has been found to result in significant delays (12).
Protocols for assessment of such patients and initiation of thrombolytic therapy have consistently and dramatically reduced door-to-drug times. The experience from several different institutions was that, prior to initiation of a protocol, door-to-drug times were between 69 and 76 median min and were reduced to between 21 and 29 min following protocol development and implementation (4,29,32). Use of critical pathways can facilitate reduction in door-to-drug or door-to-balloon times for patients with acute coronary syndromes (33,34).
Even though the NHAAP emergency department working group recommended that hospitals reduce door-to-needle time to 30 min or less (12), it was only subsequent to this recommendation that the relationship between door-to-needle time and mortality was examined in a registry of 85,589 patients at over 1400 hospitals with ST-segment-eleva-tion MI who were treated with thrombolysis. Door-to-needle times <30 min were present in only 33% of patients and were less common in women, elderly, and nonwhites. While the results showed that there was no significant increase in mortality for patients with door-to-needle times of <30 min compared with patients whose door-to-needle times were 31-60 min, the adjusted odds ratio of death was significantly increased by 11% for patients with door-to-needle times of 61-90 min (p = 0.01) and increased by 23% for patients with door-to-needle times of >90 min. Additional analysis showed a 13-23% increase in the odds for developing an ejection fraction <40% as door-to-needle time increased >30 min (p = 0.001 for each time point). These data show that a delay in door-to-needle time >60 min, which is present in about 27% of the patients, was associated with an 11-23% increase in mortality and in the development of left ventricular dysfunction post-MI, the first direct evidence that efforts to reduce door-to-needle time are warranted to improve outcome after thrombolysis (35) (Figs. 4 and 5).
The relationship between symptom-onset to balloon time and door-to-balloon time was examined in a cohort of 27,080 patients with ST-segment-elevation MI or left bundle-branch block, who were treated with primary angioplasty and reported to the
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