BALTIMORE--The implementation of several protocols, as well as outreach community education programs, resulted in a significant reduction in overall ischemic time in STEMI which correlated with a reduction in overall infarct size, according to a scientific poster presented May 4 at the 2011 Society for Cardiovascular Angiography and Interventions (SCAI) scientific sessions.
While door-to-balloon (D2B) times in ST-elevation MIs (STEMIs) have shortened over the past decade, overall mortality rates in patients with STEMIs have remained similar, according to the study authors. While there has been an improvement in DB2 times, symptom-onset-to-balloon time (SOBT)--a variable more representative of overall ischemic time--has remained unchanged.
“Symptom-onset-to-balloon time is more representative of the overall time the heart experiences a shortfall in blood and oxygen,” said lead investigator Robert Minutello, MD, an associate professor in the division of cardiology at Weill Cornell Medical College in New York City, and director of the acute coronary syndrome committee at New York Presbyterian Hospital in New York City.
SOBT incorporates both protocols and quality of care at the hospital level as well as community education and public awareness at the pre-hospital level. For this study, the researchers analyzed all STEMI cases presenting to New York Presbyterian-Weill Cornell’s emergency department from 2004 to 2010, during which time specific protocols (aligned with the Door-to-Balloon Alliance, the Society of Chest Pain Centers and the ACC/AHA/SCAI guidelines) and community-outreach programs were adopted. They measured heart attack size by the peak level of creatine kinase (CK) enzymes, which are released into the blood when the myocardium is damaged.
They sought to determine if there was a significant decrease not only in DB2 times, but also in SOBT, and whether this correlated temporally with a decrease in overall MI size as measured by peak CK levels.
Over the seven years analyzed, the researchers found a significant improvement not only in the average D2B time, but also in average SOBT and in the average heart attack size. When comparing time periods 2004 to 2007 and 2008 to 2010, peak CK levels fell from 2,625 units/L to 1,812 units/L, average SOBT fell from 270 minutes to 217 minutes and average D2B time fell from 97 minutes to 71 minutes.
“The most important finding of this study is that reducing symptom-onset-to-balloon time leads to less heart tissue death,” Minutello said.
“Symptom-onset-to-balloon times should be addressed in initiatives to improve outcomes in patients who have a heart attack,” said study co-author Mary Donna Cruz, MD, a third-year internal medicine resident at New York Downtown Hospital. “Public education and awareness campaigns are key components in these initiatives.”