Only 12 percent of people would call an ambulance if they experienced chest pains or breathlessness, both possible heart attack symptoms, during daytime on a weekday, while 28 percent would do so at night or on a holiday, according to a national study.
Receiving treatment within an hour after having a heart attack can be the difference between life and death.
The government study, released Monday, suggests that many people are reluctant to call an ambulance even if they experience unfamiliar pain or pressure in their chest or back.
A study group of the Health, Labor and Welfare Ministry interviewed 1,200 people selected at random across the nation last January.
The study found that instead of calling an ambulance, 28 percent would "consult a family member or an acquaintance" during the day, while 31 percent would do the same at night or on a holiday.
The study showed that 23 percent, if they experienced heart attack symptoms during the day, "would see how things turn out," while the figure fore night or on a holiday was 19 percent.
On why they would not call an ambulance, more than 60 percent said they would deem their plight not severe enough.
Others said they would not call because they would want "to avoid causing trouble to others," or calling an ambulance "would be too embarrassing."
Recent public opinion has been against calling an ambulance without good reason.
"An increasing number of people seem to go to the wrong hospital or try to withstand the pain," said Hiroshi Nonogi of the National Cardiovascular Center. "But a delay in getting treatment could be fatal.
"People at high risk, such as those diagnosed with high blood pressure or diabetes, must learn the signals of a heart attack and immediately call for an ambulance if something happens," he said.