A heart attack is not one size fits all. People of both sexes have experienced the grim, made-for-TV symptoms we typically expect: a cold sweat and gripping chest pain, but experts have identified more subtle signs in women, like stomach pain and shortness of breath. It’s also possible to end up in an emergency room for heart attack without noticing any symptoms at all. That would be the silent variety of heart attack, which now accounts for 45 percent of all cases, according to a new study published in Circulation — and it’s just as damaging.

"The outcome of a silent heart attack is as bad as a heart attack that is recognized while it is happening," senior study author Dr. Elsayed Z. Soliman, director of the epidemiological cardiology research center at Wake Forest Baptist Medical Center in North Carolina, said in a press release. "And because patients don't know they have had a silent heart attack, they may not receive the treatment they need to prevent another one."

Soliman and his colleagues examined not only sex differences in silent heart attacks, but racial disparity as well. They analyzed the records of nearly 10,000 middle-aged adults already enrolled in the Atherosclerosis Risk in Communities (ARIC) study, 57 percent of whom were women and 20 percent were African-American. ARIC lasted from 1987 to 1989, but researchers conducted five additional examinations throughout 2013. Atherosclerosis occurs when plaque builds up in arteries, hardens, and restricts blood vessels, a risk factor for heart attack and disease.

By the fourth follow-up visit, 317 participants had suffered a silent heart attack, which could only be detected through electrocardiogram screening, compared to 386 who had a heart attack with clinical manifestations. Men were at greater risk for both types compared to women, while blacks had a non-significantly higher rate over whites. On the flip side, whites had a higher rate of clinical heart attack than blacks. But no matter participants’ sex or race, each attack was associated with increased risk of coronary heart disease.

Interestingly, despite a greater risk among men, it was women most likely to die of a silent heart attack, at least in this study analysis. The authors believe their findings highlight the importance of detection, and the potential impact it could have on prevention methods for heart disease across the sexes and racial groups.

The ARIC sample size is larger and more inclusive than most, but because the studies the authors used for comparison were not, they said their findings speak more to the incidence of heart attacks than the significance of a patient’s prognosis, the course a disease or ailment will take.

“The problem with prior studies is that they’re mainly white or mainly men, and that’s why we can’t see if there are differences in blacks and whites and women and men,” Soliman said. “Even if there was good representation, there isn’t long-term follow-up that can really address the term of prognosis.” This is to say that exclusive studies don’t properly track whether patients who have silent heart attacks have better or worse outcomes compared those who have clinical heart attacks, Soliman added.

As it stands, there’s some inconsistency on which type has the worst prognosis: Some studies say silent heart attacks are worse, while others say both kinds are equally bad. The only way to fill some of the gaps in knowledge is to recruit a more diverse sample, Soliman said.

So while they believe their results add to growing evidence of sex and racial disparity in heart disease patient outcomes, the study authors called for future research to better “assess whether genetic background, emerging risk factors, access to health care, awareness, and adherence to medications contribute to sex and racial differences.”

"The modifiable risk factors are the same for both kinds of heart attacks," Soliman said. "Doctors need to help patients who have had a silent heart attack quit smoking, reduce their weight, control cholesterol and blood pressure, and get more exercise."

Source: Zhang ZM, et al. Race and Sex Differences in the Incidence and Prognostic Significance of Silent Myocardial Infarction in the Atherosclerosis Risk in Communities (ARIC) Study. Circulation. 2016.