The shorter the time from onset to treatment, the better the outlook.
Door-to-balloon time is the time from when a heart attack patient arrives in the emergency room until percutaneous coronary intervention is performed to restore blood flow.
ST-segment elevation myocardial infarction (STEMI) is "a severe heart attack caused by a prolonged period of blocked blood supply that affects a large area of the heart," according to the American Heart Association.
American College of Cardiology/American Heart Association (ACC/AHA) guidelines state that hospitals treating STEMI patients with emergency percutaneous coronary intervention should do so within 90 minutes or less of reaching the hospital.
The ACC launched the Door-to-Balloon (D2B) Alliance in 2006 to reduce the time to which STEMI patients receive percutaneous coronary intervention in US hospitals, and hospitals have made progress in doing so.
In about 90% of percutaneous coronary intervention cases, blood flow is restored in the surface of the heart, but in about 1 in 3 patients, blood flow is not restored to the heart muscle.
Better outcomes for patients treated within 2 hours
Researchers in this study compared the impact on heart muscle function of the time from onset until treatment with time from door-to-balloon, in other words, between arrival at the emergency department until treatment.
The team reviewed the records of 2,056 patients in the multi-center Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial; they compared patients with symptom onset-to-balloon time in three categories: 2 hours and less, between 2-4 hours, more than 4 hours.
Patients who received treatment with a balloon angioplasty to restore blood flow to the heart after 2-4 hours or longer from the onset of symptoms were less likely to have blood flow fully restored to the heart and more likely to die within 3 years than patients treated more quickly.
Study author Dr. Roxana Mehran, who is director of interventional cardiovascular research and clinical trials at the Zena and Michael A. Weiner Cardiovascular Institute at Mount Sinai School of Medicine in New York City, says:
"The decrease in median door-to-balloon time in recent years has not resulted in a reduction in mortality in STEMI patients. This study highlights the need to reconsider the role of door-to-balloon as a performance metric and examine the utility of a broader metric of systems delay such as first medical contact to balloon time as well as total ischemic time."
In an accompanying editorial, Dr. Michael A. Kutcher, of Wake Forest Baptist Medical Center, said the door-to-balloon metric and systems in place are extremely valuable and should continue.
However, he points out the need for physicians to look at associated metrics, such as the signs and symptoms of the onset of ischemia or loss of blood flow.
Dr. Kutcher believes that the reduced door-to-balloon time has not been matched by a significant improvement in mortality and morbidity because microvascular damage can still occur with shorter door-to-balloon time; this can increase the risk of death.
He says that patients with longer door-to-balloon time are a high-risk group and should be treated accordingly with assertive strategies. He wants the interventional cardiology community to continue to educate the public and health care providers regarding the importance of prompt action.
Medical News Today recently reported that women who experience a heart attack continue to be at risk of illness and death in the long term.