Women having a heart attack should demand they are seen by a female doctor - as it will probably save their lives, a new study has found.
If no female medics are available, a male doctor with plenty or female colleagues, or more than a decade of treating women, is the next best option.
That is according to a review of nearly 582,000 heart attack cases over 19 years in Florida, which confirmed a long-held theory that female surgeons provide better returns with female patients.
Researchers believe it is because female surgeons are more likely to think outside the box to find solutions for patients who do not appear to have the most obvious symptoms - something which happens often with women.
Male doctors, on the other hand, tend only to look for the classic symptoms that affect men.
Associate Professor Seth Carnahan of Washington University in St. Louis said: "You have highly trained experts with life or death on the line, and yet the gender match between the physician and the patient seems to matter a great deal.
"Our work corroborates prior research showing that female doctors tend to produce better patient outcomes than male doctors. The novel part of what we are doing is showing that the benefit of having a female doctor is particularly stark for a female patient."
The review of A&E admissions for heart attacks between 1991 and 2010 allowed the researchers to measure important factors like the age, race, and medical history of patients, hospital quality and more.
Yet even accounting for these factors, it found female patients were less likely to survive heart attacks than male patients and that gender differences in survival rates were the highest under male doctors .
For patients treated by female doctors, the gender disparity in survival rates was about 0.2 per cent.
In other words, 11.8 per cent of men died, versus about 12 per cent of women.
However, for patients treated by male doctors, the gender gap in survival more than tripled to 0.7 per cent.
In that case, 12.6 per cent of men died compared to 13.3 per cent of women.
In reviewing the conditions that most favored women patients, it found their survival rates rose as the percentage of female doctors in casualty rose, particularly if the treating doctor was male.
The 'male bias' effect also declined the more the male doctors had treated female patients.
Those mitigating factors:'suggest that having training programs that are more gender neutral, or showing how men and women might present symptoms differently, could improve outcomes for female patients," Carnahan said.
Harvard Business School associate professor Laura Huang added: "These results suggest a reason why gender inequality in heart attack mortality persists. Most physicians are male, and male physicians appear to have trouble treating female patients.
"The fact that gender concordance (that is, men treating men or women treating women) correlates with whether a patient survives a heart attack has implications for theory and practice."
A variable omitted in the study was the previous finding by other researchers that female doctors tend to perform better than male doctors across a wide variety of ailments.
Associate Professor Brad Greenwood of the University of Minnesota-Twin Cities said: "If female patients tend to be more challenging for male and female doctors to diagnose and treat, the patterns we document may reflect the fact that the most skillful physicians, i.e. female doctors provide the highest return to their skills when treating the most challenging patients, i.e. female patients."
The research is similar to another study documenting how female lawyers were less likely to advance in their firms with promotions and plum assignments when they worked for politically conservative male law partners.
The current paper, however, moves outside the employer-employee arena, where gender bias is well documented in certain circumstances.
Carnahan concluded: "Employee-customer relationships don't have as much research in this area, and you can think of a physician and a patient being a customer relationship.
"I think organisations that get this right can outperform other firms and produce better outcomes for all of their stakeholders."
The study was published in the journal Proceedings of the National Academy of Sciences (PNAS).