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Mental stress relates to myocardial ischemia in women
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Mental stress is associated with peripheral vasoconstriction leading to myocardial ischemia in women, according to new data from the MIPS study.
By contrast, in men, increased hemodynamic workload appears to be the main driver for mental stress-induced myocardial ischemia, researchers reported.
“This research is important because previous studies have shown that ... ischemia during mental stress doubles the risk of heart attack or death from heart disease,” Viola Vaccarino, MD, PhD, professor of epidemiology and medicine at Rollins School of Public Health, Emory University, and a member of the Cardiology Today Editorial Board, said in a press release. “This increased risk of adverse cardiovascular events is about the same level as that seen in people who develop reduced blood flow in the heart muscle during a conventional test such as a treadmill stress test.”
Vaccarino and colleagues analyzed 678 patients with CAD from the MIPS prospective cohort study. All patients underwent myocardial perfusion imaging before and during a public speaking stressor.
The researchers calculated rate-pressure product response and peripheral vasoconstriction. They determined mental stress-induced myocardial ischemia, defined as percent of left ventricle that was ischemic; it was also used as a dichotomous variable.
Among men, those with mental stress-induced myocardial ischemia had a higher rate-pressure product response than those without it (6,500 mm Hg bpm vs. 4,800 mm Hg bpm), but the same was not true for women, according to the researchers.
Among women, those with mental stress-induced myocardial ischemia had a lower peripheral arterial tonometry ratio than those without it (0.5 vs. 0.8), but the same was not true for men, Vaccarino and colleagues wrote.
When the researchers performed adjusted linear regression, they found that, in men, each 1,000-U rise in rate-pressure product response was associated with an 0.32% (95% CI, 0.22-0.42) increase in inducible ischemia, whereas in women, each 0.1-U fall in peripheral arterial tonometry ratio was associated with an 0.23% (95% CI, 0.11-0.35) rise in inducible myocardial ischemia.
The results were consistent regardless of conventional stress-induced myocardial ischemia.
“Our findings in the peripheral circulation also could reflect what occurs in the arteries in the heart,” Vaccarino said in the release. “Instead of dilating and increasing blood flow to the heart during stress, in women the tiny blood vessels are constricted, leading to areas of reduced blood flow. Constriction of peripheral vessels can also induce ischemia in the heart indirectly because the heart has to pump against increased resistance.”
Therefore, Vaccarino said in the release, “women with heart disease need to know that they may be vulnerable to the effects of mental stress and think about ways to protect their hearts, such as relaxation techniques and physical exercise.” – by Erik Swain
Disclosure: One author reports receiving royalties from the sale of the Emory Cardiac Toolbox.
Perspective
Back to TopHarmony Reynolds
In this study, the authors used measurement of heart rate, BP and peripheral arterial tonometry to investigate possible sex differences in mental stress-induced ischemia. Ischemia is an imbalance between supply and demand of oxygen and blood flow to the heart. Exercise is well known to provoke ischemia in patients with heart disease. Mental stress also provokes ischemia in patients with heart disease. These authors have previously shown that women are more likely than men to have ischemia due to mental stress. In this study, they sought to find out if the reasons for ischemia or alterations in coronary blood flow may be different between women and men. Measurement of coronary blood flow is typically done invasively. These authors used noninvasive methods to understand how heart rate, BP and blood vessels in another part of the body, the fingers, reacted under stress. They monitored men and women with heart disease during a mental stress test, in which they had to speak in public about a difficult topic. Some of the men and women had mental stress-induced ischemia as measured by a nuclear imaging test during the stress. The main finding is that among patients with ischemia on the nuclear test during mental stress, women had a greater degree of temporary constriction of arteries in the fingers than men, while men had a greater rise in heart rate and BP. In sum, the findings suggest that women and men who have mental stress-induced ischemia have different vascular responses to that stress.
At this time, the findings do not have implications for how we should treat women with CAD.
This is a novel avenue of research. We need to improve our understanding of the effects of mental stress on the body in the short and long term, and how this relates to heart disease. It would be interesting to understand how these findings relate to ischemia of greater degrees and ischemia in patients who do not have narrowing of large arteries by plaque (ie, CAD). It would also be nice to know how the BP and heart rate responses compared to the responses to exercise in the same patients.
The degree of ischemia on these tests was mild overall; the findings on the stress tests were subtle. It is not clear whether blood vessel constriction in the fingers, which is measured by the PAT ratio, is related at all to blood vessel constriction in the heart.
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