News:Even Crossing State Lines Improves Time to Treatment for STEMI : Mayo Clinic experience

August 7, 2007 By Grendel Burrell [mailto:grendel.burrell@gmail.com]



More than 100,000 patients have received fibrinolytic agents in randomized clinical trials (2). Fibrinolytic agents have demonstrated survival benefits but carry a 1-2% risk of stroke or intracranial hemorrhage (3). Meta-analyses and clinical trials of a strategy of primary PCI have indicated survival improvement and a lowering of rates or recurrent myocardial infarction and stroke compared with fibrinolytic therapy (4). However, the survival benefits for primary PCI compared with fibrinolytic therapy are not achieved if door-to-balloon time exceeds door-to-drug time by 62 minutes (5). Rapid initiation of either PCI or fibrinolytic therapy for STEMI is acknowledged to limit infarct size and improve survival.

The American College of Cardiology/American Heart Association guidelines for patients with STEMI undergoing PCI recommend a door-to-balloon time of < 90 minutes or a door-to-drug time < 30 minutes for fibrinolytic therapy (6). Despite massive educational efforts, this goal is achieved in a minority (<40%) of patients. The American College of Cardiology Door-to-Balloon (D2B) Quality Alliance was launched in November 2006 and over 900 hospitals in the U.S. have joined in a national effort to improve timeliness of primary PCI and share best practices. Recently, there has been an increased interest in the development of regionalized care systems to reduce the time to treatment and to increase access to primary PCI.

Ting et al describe their prospective, observational cohort of 597 patients who presented with STEMI within 12 hours of symptom onset to either Saint Marys Hospital (Rochester, MN) or to one of the 28 regional participating hospitals in Minnesota, Iowa, and Wisconsin, up to 150 miles from St. Marys. 12 of the regional hospitals were already a part of the Mayo Health System. The other 16 regional hospitals were selected to participate if the total transfer time from regional hospital to Saint Marys Hospital was achievable within 30-90 minutes and if Saint Marys Hospital was the closest hospital with 24/7 PCI capability.

A regional STEMI protocol was implemented and included a standard order set and protocol used to select fibrinolytic therapy for symptom onset < 3 hours or PCI for symptoms of > 3 hours duration. PCI was also selected if patients had a contraindication to fibrinolytic therapy or were deemed at high clinical risk (shock). The protocol included a system for a single call through which the receiving cardiologist and regional physicians could discuss the case, activate air ambulance transfer and the cardiac cath lab team. The most rapid mode of transfer was selected by a central communications center deploying three helicopters. Helicopter transfer was performed by “hot loading”, a process in which the engine is allowed to continue to run to minimize ground time to ≤ 10 minutes, similar to a MASH Unit. Additionally, when patients were transferred into Saint Marys Hospital they bypassed the emergency department and were delivered to the cardiac cath lab. Inclement weather when the helicopter could not fly caused inability to transfer in 1.0% of patients.



All 28 regional hospitals were trained on the protocol by a Mayo cardiologist and nurse coordinator through on-site visits. Routine follow up site visits were done 2-4 times/year. The nurse coordinator, Christine Bjerke, RN, and the physician program director, were available by email or phone to receive feedback and answer questions. The protocol provided feedback to all health care providers involved in a patient’s care within 24-48 hours. Ting commented on the importance of this feedback mechanism to WikiDoc, “At the end of the day, the cardiologists at Mayo Clinic are not smarter, and we did not have a newer drug or stent. We did not have faster or more helicopters. We did not build a new heart center, but we did organize and execute a better system of care where the time to open an occluded blood vessel causing a heart attack has been drastically decreased, and more patients are alive because of it. Furthermore, the changes and new system of care are relatively simple to implement and transferable to many other hospitals and geographic settings.”

For symptoms of < 3 hours duration, the patients received full dose reteplase or weight-adjusted tenecteplase and were transferred to Saint Marys Hospital immediately post drug infusion. Patients with suspected failure to reperfuse underwent immediate rescue PCI. Otherwise elective cath was performed 24-48 hours post-fibrinolytic therapy. All patients received unfractionated heparin by bolus and infusion and 75 mg clopidogrel at the time of fibrinolytic therapy initiation.

Patients with symptoms of > 3 hours duration were transferred for primary PCI if immediate transfer was available. Transfer was not possible < 5% of the time. Patients with contraindications to fibrinolytic therapy or those with cardiogenic shock, persistent ventricular arrhythmias, myocarditis, or pericarditis were immediately transferred for PCI despite the duration of symptoms.

All regional STEMI patients transferred for primary PCI received a bolus and infusion of unfractionated heparin. Low molecular weight heparin and clopidogrel were not used. In 58% of patients, eptifibatide was administered in the helicopter during transport. Eptifibatide was withheld in the remaining patients due to bleeding risk or the discretion of the receiving cardiologist. Abciximab was not used due to requirements for refrigeration and filtration, both difficult in the helicopter.

For analysis, patients were divided into three categories, the patients presenting to Saint Marys Hospital, the regional hospital patients receiving PCI, and the regional hospital patients receiving fibrinolytic therapy. Patient characteristics were similar across all groups with the exception being that more patients with cardiogenic shock initially presented to Saint Marys Hospital.

Prior to the implementation of the Mayo protocol, the median door-to-balloon time for STEMI patients at Saint Marys Hospital was 90 minutes. During the study period, the median door-to-balloon time was 71 minutes, and 75% of patients had a door-to-balloon time of < 90 minutes. For patients initially presenting to regional hospitals and transferred for PCI, the door-to-balloon time was 116 minutes with a door-to-balloon time of < 90 minutes achieved in 12%.

For patients initially presenting to regional hospitals and treated with fibrinolytic therapy, the median door-to-needle time was 25 minutes, and a door-to-needle time of < 30 minute was achieved in 70%. 36.6% of fibrinolytic-treated patients underwent immediate catheterization and rescue PCI. Fastest median time from symptom onset to treatment was achieved by the regional treatment of patients with symptoms < 3 hours with fibrinolytic therapy, per protocol. Longer door-to-balloon and door-to-needle times were associated with trends for higher in hospital mortality.

The Mayo STEMI protocol reduced door-to-balloon time at the primary PCI center, Saint Marys Hospital; however, the median door-to-balloon time for patients transferred from a 3 state area was approximately 2 hours. Yet, for those patients who presented < 3 hours, median door-to-needles times were 25 minutes. Questions remain as to whether it is preferable to initiate fibrinolytic therapy or to transfer patients for PCI. Fibrinolytic therapy carries a risk of hemorrhagic stroke and a frequent need for rescue PCI.

PCI capable hospitals must achieve < 90-minute door-to-balloon times to provide the full advantages of PCI for STEMI patients. The advantages of PCI over fibrinolytic therapy may not be evidenced in patients who experience system delays. It is clear from this real world, regional experience that door-to-needle and door-to-balloon times can be reduced and guidelines-based goals are achievable with an integrated approach between cardiology and emergency medicine, between receiving hospitals and EMS transport, and between the emergency department and the cath lab.

About the Mayo Clinic Fast Track for STEMI Protocol: The Fast Track for STEMI Protocol is an easy-to-use algorithm for hospitals within the prescribed 3-state region that do not have angioplasty services available. Consultation with a cardiologist and transfer plans are initiated with one single phone call. Clinical status follow-up is provided to the entire team who cared the patient at the referring hospital. A description of the cath or PCI, copy of the ECG, and a copy of the ECHO summary are provided. Time metrics for either door-to-balloon or door-to-needle time are provided to the regional hospital, local hospital, and transport team members for review.

For patients: Heart Attack Survival Plan: Airlifting Patients to Surgery http://online.wsj.com/article/SB118610452377986914.html?mod=hpp_us_personal_journal


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