Heart attacks are the No.1 cause of death of Americans on vacation, according to one Manhattan cardiologist. The world was in shock when “Sopranos” star James Gandolfini died of a heart attack during vacation in Italy in 2013. The husband of Facebook executive Sheryl Sandberg died the same way on vacation with his family in 2015. Manhattan cardiologist Dr. Jennifer Haythe said vacations can be stressful. “People change their routines. They eat more than usual, they may drink a lot of alcohol."