Pulse
Heart Attack or Broken Heart?
The cause of apical ballooning syndrome, which mimics myocardial infarction, is a mystery.
A 53-year-old woman arrived at a Minneapolis emergency department with chest pain radiating into her jaw. Her symptoms began shortly after she received a call from the U.S. military informing her of her 25-year-old son’s sudden death. Her initial ECG showed sinus tachycardia at 116 beats per minute with widespread T-wave changes. Initial troponin T was significantly elevated.
Although it appeared the woman was having a myocardial infarction, she wasn’t. She was, instead, diagnosed with apical ballooning syndrome (ABS), a recently recognized condition that mimics a heart attack but does so in the absence of coronary artery disease. ABS causes temporary ballooning or hyperexpansion of the apical left ventricle (LV) when that portion of the ventricle stops contracting.
“Any physician could potentially encounter this condition,” says Scott Sharkey, M.D., a consulting cardiologist at the Minneapolis Heart Institute at Abbott Northwestern Hospital. “You see it most often in the emergency department, intensive care, and postop units. But I’ve had patients walk into my exam room with it.”
ABS usually affects older women who’ve recently experienced intense emotional or physical stress. Of women admitted to the Heart Institute for suspected myocardial infarction (MI), about 6 percent had ABS, according to Sharkey. Worldwide, 1 percent to 2 percent of all patients presenting with what appears to be a heart attack have ABS, says Abhiram Prasad, M.D., a Mayo Clinic cardiologist who identified Mayo’s first case in 2002.
Because emotional distress such as the death of a loved one often triggers ABS, the condition has been nicknamed “broken heart syndrome.” First described in Japan in 1991, where it is called takotsubo cardiomyopathy (takotsubo is the name of a Japanese octopus trap that has a shape similar to the ballooning left ventricle), it usually causes no permanent damage or disability, although it can recur and is fatal in about 1 percent of patients, according to Prasad.
The Stress Connection
No one knows for sure what causes ABS. Nor is it clear why only the apex of the left ventricle is primarily affected. Researchers at Mayo Clinic and the Minneapolis Heart Institute believe it’s partly caused by a surge of catecholamine stress hormones: epinephrine, norepinephrine, and dopamine.
An acute stressful event—either physical or emotional—triggers excessive production of catecholamines. “ABS patients often have catecholamine levels two to three times higher than patients with an MI of similar severity,” Sharkey says, “and at least seven times higher than healthy adults.” And Prasad hypothesizes that the LV may be affected because the apex has more catecholamine receptors, but “the evidence for this is pretty gray. It’s based on a few animal studies.”
Making the Dianosis
Determining whether a patient is having a myocardial infarction (MI) or apical ballooning syndrome (ABS) can be a tough call, as most ABS patients present with MI symptoms: chest pain, shortness of breath, and dyspnea. “They look the same on the table,” says Scott Sharkey M.D., a consulting cardiologist at the Minneapolis Heart Institute.
For that reason, physicians need to take a thorough patient history. “Politely, discreetly determine if the patient recently experienced a stressful event,” he says. “If the answer is yes, if the patient is female, middle-aged or older, if images show no significant blockage, and if the tell-tale LV ballooning is visible, it raises the chances it’s ABS, not MI.”
To be sure, physicians need to look for some important physical distinctions. If it’s ABS, the images will show no significant coronary blockage on an angiogram. ABS usually causes a less-pronounced ST-segment elevation—about one-half to three-quarters of that typical of an MI. Half of ABS patients have no ST-segment elevation, according to a new Mayo Clinic study being prepared for publication. All ABS patients have elevated troponin, although not as high as in those who’ve had an MI. Likewise, creatine kinase myocardial band fraction is usually elevated in ABS, but not as much as in MI. In ABS, a T-wave inversion usually develops within two to three days.
ABS usually affects about two-thirds of the left ventricle, whereas a typical MI affects only that part of the myocardium receiving blood from the occluded artery. With ABS, stunning of the heart is temporary; the effects of an MI are permanent unless the obstruction is relieved rapidly, according to
Sharkey.—H.B.
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This surge of stress hormones may directly impair cardiac function or it may cause ischemia due to spasm in the microcirculation feeding the apical two-thirds of the LV. Either way, the apical LV is stunned so it no longer contracts. Sharkey likens it to a “concussion of the heart.”
Meanwhile, the basal portion of the LV continues to contract, forcefully pushing blood into the noncontracting apex of the LV, causing the apex to expand outward. “It’s like squeezing a balloon at one end,” Sharkey says.
Although catecholamine surge is the strongest hypothesis so far about the cause of ABS, it needs to be studied further as not all ABS patients have documented catecholamine surges.
Another theory is that microvascular blood flow to the LV is temporarily slowed in patients with ABS, according to Prasad. “We don’t know if this is a primary cause of ABS or a secondary phenomenon,” he says. Mayo studies show that two-thirds of ABS patients they’ve seen have abnormal perfusion in the LV.
Declining estrogen levels may be another factor, some suggest, but not all ABS patients are post-menopausal. “If estrogen does play a part,” says Prasad, “it’s a small part.” Some speculate that older women’s hearts are somehow anatomically different, but again, there’s no hard proof.
Who’s At Risk?
Most people who experience acute stress do not get ABS. So Sharkey and Prasad are looking for genetic, physiological, and anatomical markers that make some people more susceptible. So far, none has been found.
What they do know about ABS patients is that more than 90 percent are women age 50 or older who recently experienced an intense physical or emotional event. Out of 102 cases Sharkey studied, 60 percent were triggered by emotional stress and 40 percent by physical stress. At Mayo, one-third of patients had emotional triggers, one-third had physical triggers, and one-third had no identifiable stress trigger.
Emotional triggers have included sudden death of a loved one, a domestic argument, a frightening medical diagnosis, public speaking, and financial crisis. Physical triggers have included a motor vehicle accident, asthma attack, sudden onset of illness, and recovery from surgery or anesthesia. ABS also occurs in ICU patients, especially those with sepsis.
One of Prasad’s patients, a photojournalist, went into ABS while photographing U.S. soldiers leaving for Iraq. “The sight of these soldiers going to war was enough of a trigger for her,” Prasad says. One of Sharkey’s patients went into ABS after having a flat tire while alone on a country road. Another was upset because she was late getting her elderly mother to a doctor’s appointment. One patient experienced it after orthopedic surgery. Another following gallbladder surgery. Another during a lung biopsy. “She was anxious about the procedure and then the procedure itself became a co-trigger,” Sharkey says. “Emotional and physical stressors often blend together.”
Only two patients Sharkey studied were men. A severe stroke triggered ABS in one and diabetic gastroparesis triggered the other. “I don’t know why women are more susceptible,” Sharkey says. “But I believe we will ultimately find the brain response to stress is different between men and women. I don’t believe it’s directly related to sex hormones.”
Treating ABS
Because ABS is not fully understood, there are no standard treatment guidelines. Patients presenting with symptoms should initially be treated as though they are having an MI, until imaging confirms ABS, according to Sharkey and Prasad. Because a definite diagnosis of ABS can’t be made until complete recovery has occurred, Prasad recommends starting patients on standard treatment for reduced heart function. ABS patients usually receive some combination of ACE inhibitors, beta-blockers, diuretics, and aspirin, he says, often remaining on beta- blockers for several years, as the medication may help prevent recurrence.
About 10 percent of ABS patients do have a recurrence within four years, according to Mayo studies of 100 patients. Minneapolis Heart Institute has seen a 5 percent recurrence among its 102 patients. One of Sharkey’s patients had four recurrences, each following a stressful event.
ABS death rates are 1 percent compared with 5 percent for MIs. “That’s low,” Sharkey says, “for a condition where half to two-thirds of the heart is not working properly. When an MI affects that much heart, you see 15 to 20 percent mortality.” Unlike with MI, ABS doesn’t affect life expectancy, Prasad explains.
For most patients, ABS occurs once, then resolves itself. Chest pain lasts approximately one to two hours, symptoms subside when the stress trigger resolves, and LV ballooning usually goes away within one week, with no permanent damage.
In the case of the 53-year-old woman whose test results did not indicate MI, follow-up echocardiogram one week after her hospital admission showed complete recovery of LV function with an ejection fraction of 60 percent. She was given a beta-blocker and an ACE inhibitor and received grief counseling through her church. With ABS, it appears, time does mend a broken heart.—Howard Bell