Pre-Hospital ECGs Save Time For Heart Attack Patients
Lifesaving procedures to open blocked heart arteries could begin much sooner for heart attack patients if electrocardiograms (ECGs) were recorded before they arrive at the hospital and used to put treatment teams into action, according to a scientific statement in Circulation: Journal of the American Heart Association.
Each year, about 920,000 people in the U.S. have a new or recurrent heart attack, also called myocardial infarction (MI). ST-segment elevation myocardial infarction (STEMI) is a common and especially severe type of heart attack. While there are no exact statistics for STEMI, the number has been estimated between 200,000 and 400,000.
Rapid treatment to reopen the blocked artery is vital because more heart muscle dies the longer it’s deprived of blood flow.
Current criteria for evaluating quality of care includes elapsed “door-to-balloon” or “door-to-drug” time — the time span from the moment a patient enters a hospital emergency room until blocked arteries are re-opened either by angioplasty or a clot-busting drug.
However, “the clock starts ticking from the moment a person develops symptoms of a heart attack,” said Henry H. Ting, M.D., lead author of the statement and a cardiologist at the Mayo Clinic in Rochester, Minn. “The pertinent measure of system performance is from the time of first medical contact with paramedics or other emergency medical personnel to reperfusion therapy (reestablishing blood flow to the heart muscle).”
Ting and colleagues evaluated progress since STEMI guidelines were first issued by the American Heart Association and the American College of Cardiology in 2004. They were updated last year. The guidelines recommend that all emergency medical services acquire and use pre-hospital electrocardiograms to evaluate patients with suspected acute coronary syndromes.
“If pre-hospital ECGs were more widely used and integrated with systems of care, the time from first medical contact to balloon reperfusion could be reduced to less than 60 minutes,” Ting said. The recommended goal is 90 minutes or less.
Delays from the time a person has heart attack symptoms to when they receive artery-opening treatment can be divided into four time intervals: (1) symptom onset-to-EMS arrival; (2) EMS arrival-to-hospital arrival; (3) hospital arrival-to-ECG; and (4) ECG-to-reperfusion. Pre-hospital ECG programs, if effectively implemented and coordinated with comprehensive systems of care, have the potential to decrease the latter three time intervals – and eliminate the third one.
The statement presents examples of using pre-hospital ECGs, including systems of care with door-to-balloon times approaching 30 minutes or less. In these systems, pre-hospital ECGs are used to activate the cardiac catheterization laboratory while the patient is en route to the hospital, and the patient is transported directly to the cath lab (bypassing the emergency room evaluation).
Despite the recent recommendations, fewer than 10 percent of EMS systems have adopted the use of pre-hospital ECGs, and the rate has not substantially changed since the mid-1990s.
“Furthermore, even when a pre-hospital ECG is acquired, the information is often not translated into effective action to decrease delays in treatment,” Ting said. “It is a lost opportunity to improve the quality of care for STEMI patients if the information from a prehospital ECG is not used to change downstream processes of care.”
The reluctance of patients with acute coronary syndromes to call 9-1-1 is a major obstacle to realizing the full public health benefits of pre-hospital ECGs and organizing systems of care. Studies show that more than half of STEMI patients take themselves to the hospital rather than use EMS. In addition, recent studies have shown that the longest delay for STEMI patients – two hours on average – is from the time of symptom onset to hospital arrival, said Ting.
Other barriers include:
• ensuring EMS and emergency rooms have the capacity to meet demand for services;
• developing standards for education and quality assurance for EMS providers;
• improving collaboration among EMS, emergency medicine physicians and cardiologists;
• coordinating hospital networks to provide the ideal patient care;
• overcoming insurance reimbursement issues for prehospital care;
• studying unintended consequences from implementing pre-hospital ECG programs.