Supersaturated oxygen (SSO2) administered during catheter-based treatments for heart attack can significantly reduce heart muscle damage, according to a new study reported in Circulation: Cardiovascular Interventions, a journal of the American Heart Association.
In another study from the same issue, a different group of researchers found that manually removing a blood clot provided greater recovery of heart function after a heart attack.
“The greatest benefits were seen in the patients most at risk,” said Gregg W. Stone, M.D., lead author of the SSO2 study, and professor of medicine at Columbia University Medical Center in New York, N.Y. “The larger the heart attack, the more heart muscle salvaged.”
SSO2 — highly concentrated oxygen mixed in blood and delivered to the area of heart muscle dying after a heart attack — showed promise in animal studies and a previous human trial (AMIHOT-I). So Stone and his colleagues conducted AMIHOT-II with a similar protocol, focusing on patients with anterior ST-segment elevation myocardial infarctions (STEMIs) who were treated within six hours of heart attack symptoms.
“STEMIs are the large attacks,” Stone said. “They have a really bad early prognosis because there is so much heart muscle lost.” When a large area of the heart is damaged, heart failure is more likely.
Of the 733,000 Americans who suffer acute coronary syndromes (i.e. heart attack or chest pain) each year, 361,000 (almost half) have a STEMI. Catheter-based percutaneous coronary intervention (PCI) is a procedure that can effectively open blocked arteries in STEMI patients.
The AMIHOT-II researchers studied 301 STEMI patients who arrived within six hours after the onset of symptoms at 20 sites in four countries. The researchers randomized 222 to receive PCI plus SSO2 — infused for 90 minutes during treatment –– and 79 to PCI only. Some of their analyses also included data pooled from 101 patients from the AMIHOT-I.
Major study findings included:
“Some scientists have questioned the safety of SSO2 in heart patients, but only a few major and minor problems occurred in AMIHOT-II, and the study met all of its pre-defined safety endpoints,” Stone said.
In the same issue of Circulation: Cardiovascular Interventions, Francesco Liistro, M.D., and colleagues at San Donato Hospital in Arezzo, Italy, reported that manually removing a blood clot during PCI provides STEMI patients greater heart muscle perfusion and recovery of left ventricle function.
In their single-center study, researchers randomized 55 patients to clot aspiration and 56 to standard PCI. In PCI, a physician typically inflates a balloon on a catheter tip to flatten a clot against the vessel wall, and then inserts a metal-mesh stent to prop the vessel open.
Instead of using a balloon, which leaves clot debris in the blood, the team pushed a special catheter into the blockage and sucked the clot into the tube to remove it from the body before stenting.
Major study findings included:
TherOx, Inc. funded the AMIHOT-II study.
Co-authors with Liistro are: Simone Grotti, M.D.; Paolo Angioli, M.D.; Giovanni Falsini, M.D.; Kenneth Ducci, M.D.; Silvia Baldassarre, M.D.; Alessandra Sabini, M.D.; Rossella Brandini, M.D.; Eugenia Capati, M.D.; and Leonardo Bolognese, M.D.
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