Heart attacks deadlier to women

IT IS a common perception that heart attacks affect mainly men. However, in the last three decades, death from heart attacks has been consistently higher in women than men in the United States yearly.

Women are worse off

Whether within one year or five years after a heart attack, more women than men will die (26 per cent and 47 per cent of women versus 19 per cent and 36 per cent of men respectively).

In addition, women with heart attacks are also more likely to suffer from a stroke.

With almost half the women dying within five years of a heart attack, understanding the reasons for the increased fatalities in women will help us to take proactive measures to reduce the incidence of heart attacks.

A publication "Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association" in the highly regarded Circulation journal in 2016 provides interesting insight into the differences between men and women.

The increased incidence of death from heart attacks in women can be explained by the following: different risk profiles, atypical symptoms, less optimal treatments, lower likelihood of having X-ray imaging of the heart arteries, and lower likelihood of getting timely treatment to open blocked heart arteries.

These women also have longer hospital stays, higher death rates in hospital, have more bleeding complications and have up to 30 per cent more hospital re-admissions within 30 days after discharge.

Know the risk factors

Generally, women with heart attacks have a higher likelihood of having diabetes mellitus, high blood pressure, depression, and impaired kidney function as compared with men. Some risk factors such as smoking, diabetes mellitus and depression are more potent in women than men.

For non-smoking young women with no high blood pressure, no diabetes, normal blood cholesterol levels and normal body mass index, disease of the heart arteries is extremely rare. In the US, only about 20 per cent of women below 40 years of age are in this healthy cohort.

Smoking is the most important preventable cause of heart attacks in women, it increases the risk seven-fold. This risk decreases substantially within two years of smoking cessation.

High blood pressure is another major risk factor and in women, the risk of a heart attack can be reduced by 36 per cent if high blood pressure was prevented.

In older women, isolated elevation of the upper or systolic blood pressure (SBP) reading is the most common of high blood pressure. A SBP greater than 185 mm Hg increases the risk of heart related death by three-fold when compared to a SBP of 135 or less.

In women, obesity increases the risk of heart attack 3-4 fold and diabetes increases the risk of heart artery disease and heart attacks 4-5 fold.

Depression is twice as prevalent in women compared to men and increases the risk of heart attack and cardiac death by at least 50 per cent.

After a heart attack, 50 per cent of women up to 50 years of age and more than 40 per cent of women between 50 and 60 years of age meet the diagnostic criteria for major depression.

The paradox

Although women have worse outcomes following a heart attack, they are less likely to have significant obstruction of their heart arteries during heart attacks.

Autopsy studies have shown that there are three main mechanisms of an acute heart attack, namely, plaque rupture, plaque erosion, and calcific nodule. The most common mechanism of a heart attack is a plaque rupture followed by occlusion of the lumen by blood clot.

In this situation, the heart artery has a significant obstruction due to narrowing of the lumen by cholesterol deposits in the wall (plaque).

Increased speed of blood flow can cause the plaque lining to tear (plaque rupture). When that happens, the body tries to seal the tear in the lining of the artery by forming a blood clot. This blood clot can then occlude the small residual lumen and precipitate a heart attack.

A global survey by Falk published in the European Heart Journal in 2013 stated that while plaque rupture accounted for 76 per cent of fatal heart attacks in men, it was only seen in 55 per cent of women with fatal heart attacks.

Plaque rupture is rarely seen in premenopausal women, and this may be due to the beneficial effects of oestrogen.

Plaque erosion is the second most common mechanism of an acute heart attack.

At the narrowed heart artery segment, the plaque lining is eroded and small blood clots which form over the erosions may be "washed" downstream by flowing blood and the clots travel to occlude the smaller branches (micro-embolism).

Plaque erosion accounted for 27 per cent of major heart attacks and 31 per cent of minor heart attacks in autopsy studies.

Only two risk factors, female sex and premenopausal status, have been shown to predict the plaque erosion. Hence, the higher prevalence of plaque erosions in women, especially younger women, as compared to men, is consistent with the finding that heart attacks without the presence of significant blockage of the heart arteries is more prevalent in the young and in women.

About 2-7 per cent of heart attacks may be due to clot formation at the site of significant calcium deposit (calcific nodule) in the narrowed heart artery segment.

Additionally, between 7 per cent and 32 per cent of women with heart attacks have no significant blockage of the heart arteries. Women are also more likely to have unusual mechanisms of heart attack such as spasm (constriction) of the heart artery and spontaneous tear of the inner lining of the heart arteries.

Symptoms

While chest pain remains the most common symptom of a heart attack, women are less likely to have central chest pain as compared to men.

Women often present with atypical symptoms such as shortness of breath, weakness, fatigue, indigestion, pain in the upper back, arm, neck, and jaw.

Women who have a major heart attack without chest pain have a higher risk of hospital death.

This gender difference can result in misdiagnosis, delayed diagnosis, delayed testing, delayed treatment and higher death rates from heart attack.

In developed countries, those with acute heart attacks who arrive in hospital are often treated by opening the blocked heart artery causing the heart attack by the insertion of balloon catheters and metallic meshes called stents into the blocked heart artery segments via the wrist or groin arteries.

This procedure is called primary percutaneous coronary intervention (PCI).

The earlier the heart artery gets opened, the less heart muscle is damaged and the better the outcomes. Misdiagnosis and delayed diagnosis can only result in poorer outcomes.

Treatment choices

Those who have an acute heart attack are treated with clot dissolving drugs (thrombolytics) or primary PCI.

Compared to men, women given thrombolytics have higher death rates, bleeding in the brain, shock and bleeding.

W omen have better outcomes when treated with primary PCI as compared to thrombolytics. Although primary PCI reduces the risk of bleeding in the brain, the female sex remains an independent predictor of bleeding.

Women who undergo open heart bypass graft surgery have a higher risk of in-hospital deaths and are more likely to get post-operative complications such as kidney failure, neurological complications and heart attacks.

About half of women die within five years of a heart attack. For women, here are a few points to note:

Chest pain: If you have exertional chest pain and are post-menopausal, you need a heart check;

Risk factors: if you are post-menopausal and have multiple risk factors including smoking, high blood pressure, diabetes , obesity, cholesterol elevation, family history of heart disease or depression, you should consider a heart assessment even if you have no chest pain;

Atypical symptoms: If you have risk factors and recent onset of exertional shortness of breath, weakness, fatigue, or indigestion, you must seriously consider the presence of heart disease;

Early action: Misdiagnosis, delayed diagnosis, and delayed testing contribute to poorer outcomes in women and hence, do not hesitate to seek medical advice and get yourself checked early if you have multiple risk factors or have symptoms;

No check needed: non-smoking young women with no high blood pressure, no diabetes, normal blood cholesterol levels and normal body mass index rarely have heart disease;

Stents: if you have a heart attack, wherever feasible, primary PCI offers the best outcome; Prevention: stop smoking and control risk factors, and manage depression to avoid heart attacks.

Prevention is better than cure.

Dr Lim is medical director at the Singapore Heart, Stroke & Cancer Centre.

He is a professor at Fudan University, Shanghai and vice-president of both the World Chinese Doctors Association and the World Federation of Chinese Cardiovascular Physicians.

He is also founding editor of Heart Asia, a journal of the British Medical Journal Publishing Group This series is brought to you by Heart, Stroke and Cancer Centre. It is produced on alternate Saturdays.


This article was first published on March 5, 2016.
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