OTTAWA — A 43-year-old woman arrived at a rural Long Island emergency room complaining of sharp stabbing pain under her left breast, which had been on and off for the past 24 hours. She had a history of smoking and high blood pressure, but she had a normal exercise stress test two years earlier and her ECG was normal. Given her symptoms, she could have been having a heart attack or she could simply have gas. Knowing they had to act fast in case she was having a heart attack, clinicians used a point-of-care blood analyzer to test for the biomarker troponin and diagnosed her with a heart attack. She was then flown to a hospital that had a catheterization lab.