CHICAGO – A novel smartphone app performed nearly as well as a standard 12-lead ECG for diagnosis of ST-segment elevation MI (STEMI) in patients presenting with chest pain in ST LEUIS, an international, multicenter study.
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Dr. J. Brent Muhlestein
“This study demonstrates that a 12-lead-equivalent ECG obtained using a smartphone coupled with a software application and inexpensive two-wire attachment can identify STEMI versus non-STEMI with an excellent correlation to a traditional 12-lead ECG. This technology holds substantial promise to improve outcomes in STEMI by enabling more rapid diagnosis and treatment anywhere in the world for inexpensive cost,” J. Brent Muhlestein, MD, said while presenting the ST LEUIS results at the American Heart Association scientific sessions.
This technology could provide a long-sought breakthrough in overcoming patient denial and motivating hard-headed individuals with a life-threatening MI to get to the hospital more quickly after symptom onset, instead of initially shrugging off the matter as indigestion or another nuisance. If individuals can use their handy cell phone or smartwatch to quickly obtain an ECG that shows they’re having a STEMI, they’re going to seek medical attention much sooner, with resultant greater salvage of heart muscle, noted Dr. Muhlestein of Intermountain Healthcare in Salt Lake City.
ST LEUIS tested whether a smartphone ECG app developed by AliveCor can accurately diagnose STEMI in patients with chest pain. The study, which took place at Intermountain Medical Center and a handful of other sites associated with the Duke University Cooperative Cardiovascular Society, included 204 patients who presented to EDs with chest pain. They simultaneously received both a standard 12-lead ECG and an ECG obtained using the AliveCor smartphone app. The matched ECG pairs were evaluated separately, both quantitatively and qualitatively, by a blinded panel of experienced cardiologists and classified as STEMI, left bundle branch block, non-STEMI, or uninterpretable. The study population included 92 patients with chest pain and activation of a STEMI protocol and 112 who came through the ED chest pain protocol.
Side-by-side ECG comparisons weren’t attempted in 14 pairs deemed not interpretable. In 13 cases this was because of technical problems with the smartphone ECG, and in the 14th because of ventricular pacing in the standard 12-lead ECG.
STEMI was diagnosed in 22.5% of the study population by 12-lead ECG and in 29.4% by smartphone app. The discrepancy was explained by small voltage differences in the ST-segment elevation which met criteria for STEMI by smartphone but not standard 12-lead ECG in 15 cases.
“It appears that the ST elevation was a little bit more obvious in the smartphone ECG,” Dr. Muhlestein observed.
Left bundle branch block was identified in 5.4% of patients by both methods.
The key performance numbers: The smartphone ECG had a sensitivity of 89%, specificity of 84%, positive predictive value of 70%, and negative predictive value of 95% for diagnosis of STEMI or left bundle branch block. The positive predictive value was diminished by the increased likelihood that the smartphone would call STEMI in discordant cases.
Dr. Muhlestein said that, despite the AliveCor device’s very good correlation with the standard 12-lead ECG, the system needs further tweaking.
“We definitely think this is not ready for prime time. Further refinements of the software and hardware may improve on our study results and broaden potential applications through increased ease of use and reliability. I’m sure smart engineers can make a much more simple, really user-friendly device now that we know it’s actually feasible. I envision a time when you turn it on and it speaks loud and tells you what to do and how to do it – like an AED [automated external defibrillator] – then uploads the ECG to the cloud, interprets it, and tells you whether you should go to the emergency department or not,” Dr. Muhlestein said.
This is a device that’s going to be a boon not only in the United States but also in developing countries, where even people living without electricity or running water often have cell phones, the cardiologist noted.
Dr. Muhlestein reported having no financial conflicts of interest regarding the study, which was sponsored by the participating medical institutions.
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