Fear of the coronavirus is leading people with life-threatening emergencies, like a heart attack or stroke, to stay home when ordinarily they would have rushed to the emergency room, preliminary research suggests. Without prompt treatment, some patients, like Mr. Virachan, have suffered permanent damage or have died.

Emergency rooms have about half the normal number of patients, and heart and stroke units are nearly empty, according to doctors at many urban medical centers. Some medical experts fear more people are dying from untreated emergencies than from the coronavirus.

A recent paper by cardiologists at nine large medical centers estimated a 38 percent reduction since March 1 in the number patients with serious heart attacks coming in to have urgently needed procedures to open their arteries.

On a recent day at the Cleveland Clinic, there were only seven patients in the 24-bed coronary care unit. Usually the unit is full.