It’s About Time: A Regionalized Approach to Patients with AMI. August 8, 2007

August 8, 2007 By Grendel Burrell [mailto:grendel.burrell@gmail.com]

Minneapolis MN After more than 15 years of conversation, presentation, publication, and promotion, health care systems are recognizing the importance of time to treatment in patients with ST-segment elevation myocardial infarction (STEMI). The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend treatment with percutaneous coronary intervention (PCI) within 90 minutes but the goal is achieved in only 4.2% of patients (1). However, transfer of STEMI patients from as many as 210 miles to a PCI center is shown to be safe and feasible in the experience of Dr. Timothy Henry and colleagues, published in Circulation. (2).

PCI improves infarct related artery patency and improves survival while providing lower rates of recurrent myocardial infarction (MI), ischemia and stroke compared with fibrinolytic therapy. PCI is now the preferred therapy for STEMI patients when it can be performed rapidly and by experienced operators; however, PCI for STEMI is available in only 25% of US hospitals (3) (4). Clinical trials in Europe show that a strategy of transfer for PCI provides better outcomes compared with fibrinolysis at a non-PCI hospital (5) (6). In the US, the only trial attempted provides limited information since the study was stopped due to slow enrollment (7).

Henry et al developed a regional program for transfer from 30 Minnesota community hospitals to PCI centers and implemented this between March 2003 and November 2006. A standardized protocol and integrated transfer system were initiated. The specific objectives were to standardize STEMI care throughout the system, to improve timely access to PCI with door-to-balloon time <120 minutes which was the 2002 ACC/AHA guidelines, to establish a network of data collection on STEMI patients in community hospitals, to implement STEMI quality improvement measures at referring hospitals, and to improve cardiovascular outcomes in STEMI patients.

The project began out of the interests and passion for improving time to treatment of three Minneapolis physicians. Having worked on time to treatment for AMI care in the Minneapolis area for many years, Dr. Henry and Scott Sharkey, MD, teamed with David Larson, MD to survey area hospitals without cath labs on how, when, and within what time frame the institutions transferred patients for AMI care. The results were surprising. Henry stated, “Hospitals frequently reported that they had no protocols or standing orders, and that transfer was dependent on whom they called and what time of day or night.” Thus, Henry’s, Sharkey’s, Larson’s, and the Minneapolis Heart Institute physicians’ goal was to establish standardized protocol for rapid diagnosis, treatment, and transfer of STEMI patients. Funding for the study was provided by the Minneapolis Heart Institute Foundation and by Abbott Northwestern Hospital.

1345 consecutive patients with STEMI or new left bundle branch block within 24 hours of symptom onset were included. Patients with advanced age, out of hospital cardiac arrest, cardiogenic shock, and those with initially non-diagnostic ECGs were enrolled. The only STEMI or LBBB patients who were excluded were those in whom the treating physician thought that reperfusion therapy was inappropriate due to advanced metastatic cancer or end of life dementia.

A standard protocol with standing orders was established at each hospital. Hospitals were divided in zones 1 (< 60 miles) or 2 (60-210) based on the distance to the PCI center. Since weather in Minnesota can impact transfer times or the ability to transfer, the protocols included contingencies for half or full dose tenecteplase, depending on the zone. There were 19 hospitals in zone 2, and the protocol allowed a facilitated approach using half dose tenecteplase unless a contraindication to fibrinolytic therapy was evident. In zone 1 and 2, 70.5% of patients were transferred by helicopter and 29.5% by ambulance. With the obvious challenge of increased distance, zone 2 hospitals were more likely to use helicopters.

Emergency department personnel, emergency medical services, and primary care physicians at participating hospitals all received training on the protocol. “The training was done by Barbara Unger, RN, the nurse coordinator for the project, and the physicians from Minneapolis Heart. We spent time at each site with all the critical people who encounter patients with chest pain, but Barb’s role was pivotal in this,” Henry commented to WikiDoc. Each hospital was given a tool kit including a protocol checklist, transfer forms, clinical data forms, standing orders including adjunctive medications and lab work. The ECG, lab results and clinical data form were faxed to the PCI center cardiac cath lab. When patients were transferred to the PCI center, they bypassed the emergency department at the receiving hospital and were delivered directly to the cath lab.

The median door-to-balloon time for patients presenting to a zone 1 hospital was 95 minutes. From patients presenting to a zone 2 hospital the median door-to-balloon time was 120 minutes. When WikiDoc asked Henry how times at zone 2 hospitals can be improved, he replied, “The majority of the time difference is accounted for by transfer distances and thus, time. We are still need to determine the ideal strategy for managing patients with longer transport times.”

High-risk characteristics for patients presenting to the PCI center or hospitals in zone 1 or 2 were similar across all groups with the exception of out of hospital arrest that was more frequent in zone 1. 14.6% of patients were ≥ 80 years. Cardiogenic shock was present in 12.3% of patients. 10.8% of patients experienced cardiac arrest prior to PCI, and 6.9% required mechanical ventilation pre PCI.

5 of 1345 patients died prior to angiography and 4 of these presented with out of hospital cardiac arrest. Coronary angiography was performed in 99.2% of patients. PCI was attempted in 1072 patients with a 99.3% rate of success. Approximately 96% of patients experienced TIMI 3 flow after PCI. Of the 1065 patients who received PCI, 96.4% received a stent. CABG without PCI was performed in 3.6%. An additional 0.9% of patients were referred for elective CABG post successful PCI during the primary hospitalization.

There were high rates of utilization of adjunctive medications in the emergency department including ASA, clopidogrel, beta-blockers, and unfractionated heparin. 2.3% of patients received full dose fibrinolytic therapy due to transfer delays. In patients with successful PCI, 98.6% were dismissed from the hospital with aspirin, 97% with clopidogrel, 93.4% with beta blockers, 80.6% with angiotensin-converting enzyme inhibitors, and 88% with statins.

The median hospital stay was 3 days with an overall in-hospital mortality of 4.2%, and a 30-day mortality of 4.9%. If patients with cardiogenic shock or out of hospital arrest are excluded from the analysis, the in hospital, 30-day, and 1-year mortality rates are 0.9%, 1.4%, and 3.3%.

Despite training, materials, and the implementation of protocols for rapid transport, 50% of patients from zone 2 hospitals were treated >120 minutes post arrival. What is the ideal strategy for reperfusion in these patients? PCI with door-to-balloon times outside current guidelines? Full dose thrombolytics with or without transfer, including rescue PCI? A facilitated PCI approach?

In the US there is no coordinated care system for patients with STEMI. Not every hospital has a standardized, guidelines-based protocol for the diagnosis and management of patients with STEMI. When STEMI patients are transferred from non-PCI hospitals, reimbursement at the non-PCI hospital is negatively affected. Many regions lack an organized system for inter-facility transfers. The results of Henry and colleagues may provide a model through which to overcome some of these barriers to rapid identification and treatment of patients with STEMI. “To date, we’ve trained > 50 PCI centers on the development of regionalized strategies for the care of STEMI patients. There’s more to be done,” Henry commented.

Alice Jacobs, MD, who is leading the American Heart Association's Mission: Lifeline, a community-based initiative to develop systems of care for STEMI patients and increase the number of patients with timely access to primary PCI commented to WikiDoc, commented to WikiDoc, “It is critical that we educate all constituents involved in the diagnosis and management of STEMI patients, but particularly our patients, the public, and our government representatives, about the critical factor of time, because there is a clear relationship between mortality and time to treatment. Our shared goal should be nothing less than implementation of well planned, evidence-based systems to care for patients with STEMI, no matter what the location.”