Most heart attacks occur when cholesterol buildup, or plaque, blocks an artery and restricts blood flow. But a certain type of heart attack can occur with little blockage, and sometimes none at all.
Myocardial infarction with nonobstructive coronary arteries (MINOCA) heart attacks can occur when blood flow is reduced because an artery is:
- Constricted by a spasm
- Damaged
- Partially blocked (50 percent or less)
MINOCA often strikes young females. It can cause mild chest discomfort, severe chest pain or a general feeling of unease, similar to silent myocardial infarction. The cause of MINOCA often isn’t visible on imaging, and we have to do special tests to diagnose patients. Unfortunately, too many women across the country fall through the cracks and don’t get the specialized care our heart team provides.
One woman’s MINOCA story
During my cardiology fellowship in New York, an anxious woman in her late 20s came into the emergency department. She had experienced chest pain while getting ready for work, but she had no risk factors for heart attack. We reviewed her EKG, (electrocardiogram), which showed what looked like a heart attack. The patient was still shaken up, but her pain was nearly gone. We did another EKG, and her results were normal.
When I showed the young woman’s images to my attending physician, he asked if I was sure I had the correct patient’s results. They were correct, even though the results seemed unlikely! We decided to perform a catheter procedure to get to the root of the problem. We inserted a thin, flexible tube into an artery in the woman’s groin and threaded it through her blood vessels to examine her arteries.
We were glad we did the procedure—we discovered that she’d suffered a spasm in one of her arteries. It had reduced blood flow to her heart, causing a MINOCA heart attack.
4 types of MINOCA
MINOCA is an umbrella term for a group of a heart conditions that can cause a heart attack, even if an artery isn’t totally blocked by plaque. MINOCA can happen without explanation. However, it also shares the same risk factors as traditional heart attacks, including family history, high blood pressure and smoking.
MINOCA heart attacks often are caused by major or microvascular artery dysfunctions, such as the four conditions below.
1. Coronary vasospasm
Like the muscles in your arms or legs, the muscles in your blood vessels can suddenly spasm and constrict blood flow—often without explanation, and often overnight.
Coronary vasospasms can be associated with magnesium deficiencies and Raynaud’s disease, which involves vascular constriction of the fingers and hands. Women who have vascular migraines also are at increased risk. In fact, some migraine treatments can cause spasms. Use of cocaine, marijuana, excess alcohol and amphetamines can cause coronary spasms as well.
2. Microerosion of eccentric plaque
This type of MINOCA can occur when plaque deposits are disproportionate within an artery and tiny pieces of one breaks off. This can cause certain areas of the artery to narrow, restricting blood flow.
3. Microvascular disease
Damage to the walls of the small arteries in the heart can cause problems with blood flow, which can result in a heart attack.
4. Stress cardiomyopathy
Intense physical or emotional stress can cause heart muscle weakness. This condition can occur suddenly and can be severe.
How we detect and treat MINOCA
Unlike larger artery spasms, MINOCA spasms often cannot be detected on regular imaging. We can diagnose microvascular disease in our cardiac catheterization lab. Patients are given medication that causes controlled spasms, so our vascular specialists can watch to see which arteries narrow. Microerosions of plaque can dissolve quickly, often before patients can get to the lab. We can use intravascular ultrasound and optical coherence tomography to detect microerosions of plaque.
Treatment for microvascular dysfunction depends on the underlying cause. The Swedeheart Register study followed patients with MINOCA to find out which treatments have been most beneficial in the long term. Data suggest that statins are the most beneficial in preventing future events. The study also suggests that patients should quit smoking, take nitrates and take calcium channel blockers to reduce their risk for MINOCA.
If you experience chest pain, go to the emergency room. MINOCA can be severe and life-threatening, even if the pain isn’t intense. Particularly for women, if you feel like something is wrong—even if your initial testing is normal—ask the doctor if more advanced heart imaging, either inpatient or outpatient is appropriate. You are your own best advocate, and you should feel empowered to get answers to your heart-health questions.
