No lions, giraffes, or hippopotami were observed during a SAFARI led by doctors at the University of Ottawa Heart Institute (UOHI). However, doctors did get an unexpected surprise: important new insight into how best to treat patients after a severe heart attack.
Thanks to the SAFARI-STEMI trial, a clinical study which attempted to determine if radial access (through the arm) improves survival when compared to femoral access (through the leg) in patients referred for primary percutaneous coronary intervention (PCI) after a severe heart attack, physicians now believe there is no clinically important advantage to choosing either strategy despite literature to suggest radial access is associated with lower mortality rates and bleeding.
“We have shown adequately trained operators should be able to achieve similar results using either strategy for PCI,” said Dr. Michel Le May, the study’s primary investigator. SAFARI-STEMI is an acronym of the study’s title, The Safety and Efficacy of Femoral Access Versus Radial for Primary Percutaneous Coronary Intervention in ST Segment Elevation Myocardial Infarction. A STEMI is the shortened form of ST segment elevation myocardial infarction, a heart attack in which the coronary artery is completely blocked, and parts of the heart are deprived of rich oxygenated blood.
“We were initially expecting there would be a survival benefit with the radial approach,” said Dr. Le May, however the study did not show this. “The results in the radial access group were expected, however, we did a lot better with the femoral access group, which accounts for our results. The low mortality in both groups speaks highly for the UOHI.”
Dr. Le May is an interventional cardiologist at the UOHI and the founder and director of its Regional STEMI Program, which has resulted in a 50% reduction in mortality in STEMI patients in the Ottawa region since 2014. Dr. Le May presented SAFARI-STEMI trial findings at the American College of Cardiology’s 68th Annual Scientific Session & Expo (ACC 2019) in New Orleans, Louisiana, USA in March.
SAFARI-STEMI was an investigator-driven, randomized open-label trial conducted by investigators at the UOHI, in collaboration with four other centres across Canada, including St. Boniface General Hospital in Winnipeg, the New Brunswick Heart Centre at Saint John Regional Hospital, the Thunder Bay Regional Health Sciences Centre, and the Queen Elizabeth II Health Science Centre in Halifax, Nova Scotia.
In total, 2,292 adult patients were included in the study and were randomly assigned to one of two study arms, receiving either intervention via transfemoral (through the leg) access (n = 1,156) or transradial (through the arm) access (n = 1,136).
The primary outcome was all-cause mortality at 30 days. The rate of this however was discovered to be much lower than originally expected, occurring in just 1.5% of the radial group compared with 1.3% of the femoral group.
Secondary outcomes included stroke, reinfarction, stent thrombosis and bleeding, though no obvious distinctions between either access site strategy was made.
An independent Data Safety and Monitoring Board (DSMB) oversaw the safety and scientific validity of the trial, and on December 7, 2018 the trial was terminated because no clear advantage to either access site was determined.
“Over a number of meetings the DSMB had recognized that the event rate in terms of mortality was lower than had been expected,” says Dr. Le May. “The DSMB requested a futility analysis which was done, and then the DSMB got back to us, the steering committee met, and the trial was terminated.”
The futility analysis – that is the assessment of the trial’s likeliness or inability to achieve its objectives – determined an index of just 0.83 for the primary outcome of all-cause mortality, meaning the SAFARI-STEMI trial had failed to show that radial access was superior to femoral access in primary PCI.
“I think clinical trials are there to guide us in terms of what we do best for our patients,” said Dr. Le May. “I think right now there are some cases in which a physician may feel more comfortable, or perhaps more skilled at implementing one strategy over another. I think that moving forward [the operator] should choose their preferred approach.”
Dr. Le May believes the study also suggests that interventional cardiologists should aim to become better transfemoral operators, because data shows either strategy can achieve similar results.
- Dr. Peter Block interviews presenter Dr. Michel Le May regarding SAFARI-STEMI: femoral access vs. radial access for primary PCI in STEMI at ACC 2019.