Panic Attacks May Be an Independent Risk Factor for Cardiovascular Disease

October 8, 2007 — A new analysis of data from a substudy of the Women's Health Initiative Observational Study suggests panic attacks may be an independent risk factor for cardiovascular morbidity and mortality.
Postmenopausal women in this study who reported having had a panic attack in the previous 6 months had a 4-fold increased risk for coronary heart disease (CHD) and a 3-fold increased risk for the combined endpoint of CHD and stroke for approximately 5 years of follow-up. The risk persisted after controlling for known cardiovascular risk factors and was similar in magnitude to other established risk factors.
"Although it was quite a significant increase in relative risk, the absolute numbers of women who had those outcomes was still relatively small," first author Jordan W. Smoller, MD, ScD, from Harvard Medical School and Massachusetts General Hospital in Boston, told Medscape Psychiatry.
"On the clinical side, this may identify a subgroup of women who warrant additional monitoring or assessment of their overall cardiac risk," Dr. Smoller said.
The report appears in the October issue of the Archives of General Psychiatry.
Depression, Phobic Anxiety, Panic Attacks
The new findings related to panic attacks are consistent with previous studies that have implicated negative emotional states and psychological symptoms in cardiovascular outcomes, Dr. Smoller said. For example, previous work has shown an association between depression and phobic anxiety and cardiovascular morbidity and mortality. "This is the first large prospective study to look at panic attacks in particular," he said.
Panic attacks involve sudden episodes of fear, anxiety, or extreme discomfort accompanied by 4 or more associated cognitive or autonomic symptoms, the study authors write. Panic attacks may occur sporadically or as a feature of several anxiety disorders, including panic disorder, social anxiety disorder, and specific phobias.
The present report, called the Myocardial Ischemia and Migraine Study (MIMS), is an ancillary study of the Women's Health Initiative Observational Study, an ongoing, multicenter prospective survey of risk factors for heart disease, cancer, fractures, and other causes of morbidity and mortality among 93,676 postmenopausal women.
MIMS was carried out at 10 of the 40 centers that participated in the Women's Health Initiative. Included were 3369 community-dwelling, generally healthy postmenopausal women aged 51 to 83 years. They were enrolled between 1997 and 2000 and completed a questionnaire about the occurrence of panic attack within the last 6 months.
The study authors report that 10% of women reported full-blown panic attacks. "It was surprising how common it was," Dr. Smoller said. "We had a somewhat broad definition of panic attacks, but previous studies had suggested the frequency would not be as high as 10%, but closer to 1% or 2%."
A 6-month history of panic attack was associated with a 4-fold increase in CHD, as well as an increased risk for the combined endpoint of CHD and stroke. After excluding those with a history of cardiovascular and cerebrovascular events, there was still an increased risk for all-cause mortality associated with panic attacks.
"The study doesn't really address whether this is a direct effect of anxiety on the cardiovascular system or whether panic attacks were a proxy for some other risk factor, although we controlled for known risk factors and it did not seem due to those," Dr. Smoller said. It is possible that because panic attacks have symptoms that overlap with cardiovascular and pulmonary disease, these symptoms may represent unrecognized symptoms of underlying disease, he noted.
However, there is evidence from previous studies that physiologic aspects of panic attacks have effects on the cardiovascular system. For example, panic attacks can reduce heart rate variability. Stress hormones that accompany panic attacks can have adverse effects on the cardiovascular system or increase cardiac ischemia, "but again, at this level, it's just a hypothesis because we were not able to look directly at that," Dr. Smoller said.
"We also don't know from this study whether treating panic has any effect on cardiac outcomes, and that would obviously be an important question for follow-up studies," he noted.
Finally, Dr. Smoller pointed out that because the question asked was simply whether these women had had a panic attack in the last 6 months, those who said they had would include both those with a single panic attack and those with chronic, severe, recurrent panic disorder. "So we can't look at the effect of frequency or severity of the panic in the association here. For example, panic attacks can occur as part of a number of psychiatric conditions including anxiety disorders and depression, or sometimes be related to medical conditions, or substances, or medications, and we couldn't really tease that apart."
The Women's Health Initiative program is funded by the National Heart, Lung, and Blood Institute, US Department of Health and Human Services. Glaxo Wellcome (now GlaxoSmithKline) has funded the MIMS. Dr. Smoller has disclosed receiving honoraria from Hoffman-La Roche, Inc; has served on an advisory board for Roche Diagnostics Corp; and may receive an honorarium for a lecture he may give to an Eli Lilly and Co Advisory Board in the near future. The complete list of disclosures is available in the original article.
Arch Gen Psychiatry. 2007;64:1153-1160.