The 64-year-old patient arrived at a hospital in Brooklyn with symptoms looking like those seen in patients having a serious heart attack. An electrocardiogram revealed an ominous heart rhythm. The patient had high blood levels of a protein called troponin, a sign of damaged heart muscle. Doctors rushed to open the patient’s blocked arteries — but found that no arteries were blocked. The patient was not having a heart attack. The culprit was the coronavirus. The Brooklyn patient recovered after 12 days in the hospital and is now at home. But there have been ...