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Journalism of Courage
A 65-year-old woman with a history of Type 2 diabetes was managing her diabetes well with a healthy diet, regular exercise and medication as prescribed by her doctor. However, she had not been feeling quite herself lately. She had been experiencing shortness of breath, fatigue and chest discomfort, but she attributed these symptoms to her age and diabetes. She was referred to me for 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 had caused the silent heart attack. She underwent angioplasty and is currently on regular follow-up.
Another 50-year-old smoker with a history of exertional breathlessness and wheezing was being treated for asthma control with no noticeable benefit. This gentleman was again referred to me for evaluation which revealed heart failure as the reason for his symptoms. Heart failure had been caused by a silent heart attack. He improved with heart failure treatment and appropriate management of his Coronary Artery Disease (CAD).
Incidental findings are common in medicine and often lead to diagnostic and management dilemmas. One such perplexing patient group — individuals without symptoms who are found to have a previously undiagnosed heart attack or silent myocardial infarction (SMI) — is increasing in prevalence at an alarming rate.
People often don’t know they’ve had a silent heart attack until weeks or months later when a healthcare provider finds heart damage. Missing signs or symptoms normally unrelated to a heart attack can make it tricky to identify a silent heart attack. But it still causes damage like any other heart attack, hence it is a matter of great concern. If you have ever seen a movie where an actor has a heart attack, you’ve probably seen them clutch their chest, groaning with severe crushing pain, drenched in sweat, eyes rolling back before they collapse onto the floor. Since a silent heart attack doesn’t produce any noticeable symptoms, it goes unrecognised by the patient.
WHAT IS A SILENT HEART ATTACK?
A heart attack is called “silent” when it has no symptoms, mild symptoms or symptoms people don’t connect to a heart attack. SMI symptoms can feel so mild, and be so brief, they often get confused for regular discomfort or another less serious problem, very commonly dismissed as “gas”, flu like symptom and thus ignored.
HOW DOES A SILENT HEART ATTACK AFFECT THE BODY?
The heart needs oxygen-rich blood to function. If plaque (comprising cholesterol and other substances) builds up in the walls of arteries supplying blood to the heart, this blood flow is significantly reduced. The blood flow can be completely cut off when there is a rupture of the plaque followed by blood clots occluding the lumen of the artery leading to a heart attack. Less often, a coronary artery spasm can cut off the blood flow. The longer the heart has no blood flow, the more damage that occurs.
In SMI, because there is no pain, a person may not know they have suffered a heart attack and may not seek medical attention in time. Without timely treatment, silent heart attacks can be deadly. These can happen in sleep or wide awake. They can happen when one just goes through something very physically or emotionally stressful or becomes quickly more physically active and even when physically active outside in the cold. A 2018 study found that people who have had a silent heart attack have the same long-term survival as those who have had ordinary heart attacks. The authors found that about half of all survivors of a silent heart attack died within 10 years of the incident, which is the same rate as for survivors of other heart attacks. However, people who have had a silent heart attack are at risk of other complications, such as heart failure and stroke. According to another 2018 study, a person who has had a silent heart attack has an estimated 35 per cent higher risk of heart failure than a person without a history of heart attacks. People in their early 50s or younger have an even greater risk.
HOW COMMON IS A SILENT HEART ATTACK?
Fifty to 80 per cent of all heart attacks are estimated to be silent in various populations. According to the American Heart Association, SMI accounts for about 170,000 of the estimated 805,000 heart attacks in the US.
WHO DOES A SILENT HEART ATTACK AFFECT?
It is estimated that silent heart attacks are commoner in women, the elderly and in diabetics. Risk factors for a silent heart attack, which are the same as for a recognised heart attack, include:
High Cholesterol
Hypertension
Obesity and lack of physical activity
Smoking
Age
A family history of heart disease
Poor diet and lifestyle
Diabetes
WARNING SIGNS AND SYMPTOMS
Although, some people may not experience any symptoms or signs of a silent heart attack; others may experience non-specific symptoms that they do not connect to a heart attack like,
· Indigestion
· A feeling of a strained muscle in the back or chest
· Shortness of breath
· Dizziness
· Nausea
· Fatigue, malaise, and anorexia
· Sweating and trouble sleeping
WHY ARE SOME HEART ATTACKS SILENT?
Mechanisms that have been proposed to explain the development of silent myocardial ischemia include:
●Inability to reach pain threshold during a heart attack. Some individuals may a higher pain threshold than others
●Lesser 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 like CKD, blunted nerve response to pain due to neuropathy occurs
●Higher beta-endorphin and steroid levels masking symptoms
●Higher production of anti-inflammatory cytokines, which may block pain transmission pathways and increase the threshold for nerve activation
HOW IS SILENT HEART ATTACK DIAGNOSED
The bad news: Most SMIs are diagnosed much later due to failure in recognition of the condition.
The good news: SMIs are easily diagnosed by
· Physical examination with
· ECG
· ECHOCARDIOGRAPHY
· BLOOD TESTS LIKE CARDIAC TROPONINS
· CORONARY ANGIOGRAPHY
· CT CORONARY ANGIOGRAPHY
· CARDIAC MRI
· STRESS TESTS: EXERCISE/ NUCLEAR
MANAGEMENT OF SILENT HEART ATTACK
Long-term management of patients with SMI due to obstructive coronary artery disease should not differ from that of clinically recognised myocardial infarction, as lack of overt clinical symptoms at the time of presentation has no relation to the severity of underlying atherosclerotic coronary artery disease or indeed long-term prognosis. Optimal medical therapy along with coronary revascularization with either angioplasty or bypass surgery (to re-establish blood flow in the blocked artery) should be done as per Cardiologist’s advice.
SECONDARY PREVENTION (prevention of future heart attacks) and PROGNOSTIC EVALUATION (Tests to assess complications, efficacy of treatment and future risks) should be carried out under guidance of a cardiologist during regular follow-ups. Secondary prevention begins with risk factor modification, including lifestyle intervention (eg, healthy eating, weight reduction, regular exercise, and smoking cessation), and treatment to correct high 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 doesn’t feel right. Knowing the subtle signs of a silent heart attack can help you identify one. Be sure to get regular check-ups with your cardiologist. You can also help yourself by treating medical problems that can lead to a heart attack. Switching to a healthier diet and adding exercise can help substantially. A long-term outlook depends on rapidity of diagnosis which is based on a high index of suspicion.
