A 65-year-old woman with a history of type 2 diabetes managed her diabetes well with a healthy diet, regular exercise, and medication prescribed by her doctor. However, she hadn’t been quite herself lately. She suffered from shortness of breath, fatigue and chest discomfort, but attributed these symptoms to her age and diabetes. She was referred to me for an evaluation and investigations revealed that the patient had suffered a silent heart attack. Coronary angiography revealed that she had significant blockages in her coronary arteries, which caused the silent heart attack. She underwent angioplasty and is currently being monitored regularly.
Another 50-year-old smoker with a history of exertional shortness of breath and wheezing was being treated for asthma control without noticeable benefit. This gentleman was again referred to me for an evaluation which revealed heart failure as the reason for his symptoms. The heart failure had been caused by a silent heart attack. He improved with treatment for heart failure and proper management of his coronary artery disease (CAD).
Incidental findings are common in medicine and often lead to diagnostic and management dilemmas. One of these groups of perplexed patients – people without symptoms who present with an undiagnosed heart attack or silent myocardial infarction (SMI) – is increasing in prevalence at an alarming rate.
Often people don’t know they’ve had a silent heart attack until weeks or months later a medical professional discovers heart damage. The absence of signs or symptoms normally unrelated to a heart attack can make it difficult to identify a silent heart attack. But it still causes damage like any other heart attack, so it’s a matter of great concern. If you’ve ever seen a movie in which an actor has a heart attack, you’ve probably seen him clutching his chest, moaning in intense pain, drenched in sweat, his eyes rolling back before collapsing to the floor. Since a silent heart attack produces no noticeable symptoms, it is not recognized by the patient.
WHAT IS A SILENT HEART ATTACK?
A heart attack is said to be “silent” when it has no symptoms, mild symptoms, or symptoms that people don’t associate with a heart attack. Symptoms of IMS can seem so mild and be so brief that they are often mistaken for regular discomfort or another less serious problem, very often referred to as “gas”, a flu-like symptom and therefore ignored.
HOW DOES A SILENT HEART ATTACK AFFECT THE BODY?
The heart needs oxygen-rich blood to function. If plaque (composed of cholesterol and other substances) builds up in the walls of the arteries supplying the heart, this blood flow is greatly reduced. Blood flow can be completely cut off when there is a rupture of plaque followed by blood clots blocking the lumen of the artery resulting in a heart attack. Less often, a coronary artery spasm can cut off blood flow. The longer the heart has no blood flow, the greater the damage that occurs.
In IMS, because there is no pain, a person may not know they have had a heart attack and may not see a doctor in time. Without prompt treatment, silent heart attacks can be fatal. These can occur during sleep or while awake. They can occur when a person is going through something very stressful physically or emotionally or quickly becomes more physically active and even when physically active outside in the cold. A 2018 study found that people who had a silent heart attack had the same long-term survival as those who had a regular heart attack. The authors found that about half of all silent heart attack survivors died within 10 years of the incident, which is the same rate as survivors of other heart attacks. However, people who have had a silent heart attack are at risk for other complications, such as heart failure and stroke. According to another 2018 study, someone who has had a silent heart attack has an estimated 35% higher risk of heart failure than someone without a history of heart attack. People in their early 50s or younger are at even greater risk.
How common is a silent heart attack?
It is estimated that 50-80% of all heart attacks are silent in various populations. According to the American Heart Association, MPS accounts for about 170,000 of the estimated 805,000 heart attacks in the United States.
WHO AFFECTS A SILENT HEART ATTACK?
Silent heart attacks are thought to be more common in women, the elderly, and diabetics. Risk factors for a silent heart attack, which are the same as for a known heart attack, include:
High cholesterol
Hypertension
Obesity and lack of physical activity
Smoking
Age
A family history of heart disease
Bad diet and lifestyle
Diabetes
WARNING SIGNS AND SYMPTOMS
However, some people may not experience any symptoms or signs of a silent heart attack; others may experience nonspecific symptoms that they do not relate to a heart attack such as,
indigestion
A feeling of a tight muscle in the back or chest
shortness of breath
Dizziness
· Nausea
Fatigue, malaise and anorexia
sweating and sleep disturbances
WHY ARE SOME HEART ATTACKS SILENT?
Mechanisms that have been proposed to explain the development of silent myocardial ischemia include:
● Inability to reach the pain threshold during a heart attack. Some people may have a higher pain threshold than others
●Less severity and shorter duration of ischemic episodes (episodes of reduced blood supply)
● Generalized defective perception of painful stimuli: In diabetics, the elderly, and in conditions such as CRF, a blunted nerve response to pain due to neuropathy occurs
● High levels of beta-endorphin and symptom-masking steroids
● Higher production of anti-inflammatory cytokines, which can block pain transmission pathways and increase the nerve activation threshold
HOW A SILENT HEART ATTACK IS DIAGNOSED
The bad news: Most IMS are diagnosed much later due to a failure to recognize the condition.
The good news: MMS is easily diagnosed by
Physical examination with
ECG
ECHOCARDIOGRAPHY
BLOOD TESTS LIKE HEART TROPONINS
CORONARY ANGIOGRAPHY
CT CORONARY ANGIOGRAPHY
CARDIAC MRI
STRENGTH TESTS: EXERCISE/ NUCLEAR
SILENT HEART ATTACK MANAGEMENT
The long-term management of patients with IMS due to obstructive coronary artery disease should not differ from that of clinically recognized myocardial infarction, since the absence of overt clinical symptoms at the time of presentation has not no relation to severity of underlying atherosclerotic coronary artery disease or even long-term prognosis. Optimal medical treatment as well as coronary revascularization with angioplasty or bypass surgery (to restore blood flow in the blocked artery) should be performed as advised by the cardiologist.
SECONDARY PREVENTION (prevention of future heart attacks) and PROGNOSTIC EVALUATION (Tests to assess complications, treatment effectiveness and future risks) should be performed under the direction of a cardiologist during regular follow-ups. Secondary prevention begins with risk factor modification, including lifestyle intervention (eg, healthy eating, weight loss, regular exercise, and smoking cessation) and treatment to correct hypertension blood pressure, reduce low-density lipoprotein cholesterol and improve glycemic control in diabetic patients.
It’s best to know what’s normal for your body and get help when something isn’t right. Knowing the subtle signs of a silent heart attack can help you identify one. Be sure to have regular check-ups with your cardiologist. You can also help yourself by treating medical conditions that can lead to a heart attack. Switching to a healthier diet and adding exercise can help a lot. A long-term perspective depends on the rapidity of the diagnosis which is based on a high index of suspicion.