Treating Heart Attacks Should Begin in the Ambulance,
New Study by UT-Houston Cardiologists Shows
HOUSTON – (Oct. 16, 2007)–Cardiologists have long known that the faster they treat a heart attack once a patient arrives at the hospital, the better the patient’s outcome. But there have been more questions than answers for how best to manage patients’ care during that window of time between the onset of symptoms and their transport to the hospital.
Should ambulance services transport heart attack patients to the nearest hospital?
What if that hospital isn’t equipped to stop a heart attack? Should the ambulance travel to a hospital that specializes in the care of heart attacks, even if the facility is farther away?
What if treatment was initiated before the patient even arrived at the hospital? Would that be safe? How would that affect patient outcomes?
Richard W. Smalling, M.D., Ph.D.
Physician researchers at The University of Texas Medical School at Houston have spent years studying these questions. Today, answers are revealed in an article published in the Journal of the American College of Cardiology.
Richard W. Smalling, M.D., Ph.D., professor in the Division of Cardiology and holder of the just-announced, $1-million James D. Woods Distinguished Chair in Cardiovascular Medicine, led a pilot trial that analyzed treatment given in the ambulance followed by urgent coronary intervention.
Between September 2003 and January 2006, 73 patients were enrolled in the trial. One group of patients was given a drug cocktail, including a half dose of a clot buster, prior to arrival at Memorial Hermann – Texas Medical Center. This was followed by a second dose of clot buster and treatment in the coronary care unit.
Another group was given the same drug cocktail – a half dose of reteplase (clot buster), plus the blood thinner, heparin, and oral aspirin. Upon their arrival at the hospital, patients in this second group where immediately taken to the cardiac catheterization lab for angioplasty, or percutaneous coronary intervention (PCI), to reopen blocked arteries.
A third group of patients was ineligible for the pre-hospital fibrinolytic (clot busting) treatment, and the fourth group included patients who were transported by emergency medical systems units that were not participating in the clinical trial. These two groups of patients were treated with angioplasty in the catheterization lab.
The findings overwhelmingly supported that a half dose of the drug cocktail, followed by an interventional procedure in the catheterization lab was the most effective heart attack treatment. The study also demonstrated that the drug cocktail did not increase a patient’s risk of bleeding.
By the time they were taken to the catheterization lab, 82 percent of the patients who received the reduced-dose fibrinolysis had an improved blood flow grade, compared with less than 40 percent of the patients who were treated with angioplasty alone.
Almost 70 percent of the patients who received the reduce dose experienced a full restoration of blood flow to the heart following angioplasty, compared with only 22 percent in the groups that went straight to the cath lab without pre-hospital medication.
Also, almost 70 percent of patients who received the full dose and were scheduled to go to the coronary care unit for further care required angioplasty earlier than scheduled to resolve their chest pain and stop the heart attack.
“This suggests that PCI immediately after pre-hospital fibrinolysis should be the standard of care,” said Smalling, director of interventional cardiovascular medicine at Memorial Hermann – TMC.
James McCarthy, M.D.
“Taking a patient to the closest hospital and only giving them fibrinolysis doesn’t get the job done. Taking a patient to a PCI center for primary PCI, without getting pre-hospital clot busting treatment, delays reopening the heart attack artery by at least an hour. What we’ve showed is that you really need to do both – reduced dose pre-hospital fibrinolysis and urgent PCI.
James McCarthy, M.D., assistant professor in the Department of Emergency Medicine at the UT Medical School at Houston and medical director of the Emergency Center at Memorial Hermann – TMC, said the pilot trial demonstrated that it is safe to bypass the nearest hospital and transport a patient farther to a hospital that specializes in the care of heart attacks.
“As long as the patient gets the drug in the ambulance, it is worth the drive to a PCI center,” McCarthy said. “While they are in route, we can mobilize the cath lab so we are ready when they get here.”
Smalling and McCarthy said the pre-hospital treatment is just one step in a well-orchestrated process to get heart attack patients the fastest, most effective care.
“For every 30-minute delay, there is a 7 percent increase in mortality at one year,” McCarthy said. “Time is heart muscle, so the faster we can initiate treatment, the better the outcomes for patients.”
Smalling, who also holds the Jay Brent Sterling Professorship in Cardiovascular Medicine, said there are still questions to be answered. The pilot trial is just the beginning. He and a colleague at The University of Texas School of Public Health are applying to the National Institutes of Health for funding to establish a large, multi-center trial that would further explore pre-hospital treatment, coronary intervention and patient outcomes.
Another colleague, Ali Denktas, M.D., assistant professor in the Division of Cardiology, is conducting an analysis of a large number of heart attack patients. Preliminary findings show that the initiation of treatment in the field before the patient arrived at the hospital dramatically decreased mortality and lowered the risk of another heart attack compared to performing only emergency angioplasty.
“It looks like our initial predications almost eight years ago were correct, but we still need to conduct a larger clinical trial to substantiate what we found in the pilot trial,” Smalling said.
For the full publication online, visit http://content.onlinejacc.org/cgi/content/full/50/16/1612