What Is A Silent Heart Attack?

Introduction

Heart attack, medically known as myocardial infarction (MI), is a coronary artery disease ( CAD) and a leading cause of death worldwide. It occurs when blood flow is difficult in the heart or when the oxygen level in the blood (which flows to the heart) is reduced. A heart attack generally shows symptoms of chest pain, known as angina pain. But, there is also a condition of infarction that shows no signs or symptoms, called silent heart attack. Unfortunately, its prevalence has increased exponentially, with most cases resulting in death. This article will discuss various aspects of silent heart attack from atypical symptoms to diagnosis, risk factors, prevention, and treatment.

Understanding silent heart attack

A silent heart attack can be defined as an ischemic condition that shows no noticeable symptoms or signs. It occurs when there is an imbalance of oxygen in the heart or a blockage in the artery. Every third attack is silent, which makes it difficult to diagnose heart attacks. Silent heart attack has a concerning mortality rate. They are prevalent in patients with prior cardiovascular conditions.¹

Lack of noticeable symptoms

In the case of a heart attack, the symptoms are pain in certain body parts, commonly on the left-hand side and chest. However, in silent attacks, the symptoms are unnoticeable even to medical experts, which makes them more difficult to diagnose.

There are certain atypical symptoms like nausea, vomiting, shortness of breath, and dizziness.

Sleep disturbance a few weeks before a heart attack is a common symptom in youth. Young patients also feel tiredness, sleeplessness, anxiety, and tingling in their arms. People assigned female at birth (AFAB) are more likely to have atypical symptoms: they feel pain in another region than the chest, prominent in the jaw, neck, back, and abdomen. These uncommon symptoms result in late medical intervention. 

Prevalence and risk factors

Silent myocardial infarction (SMI) is more prevalent in people assigned male at birth (AMAB) than in people AFAB. However, the mortality is high in the latter because the uncommon symptoms make it difficult to understand the actual reason. People AMAB tend to have the risk of heart attack a decade earlier. Age and prior medical conditions play an important part in the occurrence of MI. Asian people AMAB are most prone to SMI followed by whites, Hispanics, and lastly the ones of African-American origin.² In the aged group the chance of SMI increases tenfold.³

Several risk factors increase the chances of MI other than age and gender. A study showed that the risk of SMI was higher in diabetic patients, mostly in patients with type diabetes in comparison to non-diabetic people, even in pre-diabetic men the risk was higher.

Other risk factors are high blood pressure or hypertension, prior heart disease, glucose intolerance, micro or macro albuminuria, and active smoking common factors of MI in any age group and gender.³ In people AFABthese factos include obesity, stroke, kidney or lung disorder. In people AMAB, these are cardiac arrhythmia, hyperlipidemia, and coronary artery stenosis.²

Diagnosis

As mentioned earlier, silent heart attacks are usually undetected. There are several methods designed to detect silent ischemia:

• The most common is a stress test, either a treadmill test or in combination with an electrocardiograph (ECG). This test has vast clinical support, but it can only be monitored for a short time and only in stressful conditions. Other tests include invasive myocardial hemodynamics, dobutamine ECG, and positron emission tomography. Another commonly used diagnostic test is the Holter monitor, which has the advantage of recording data for a longer duration during daily activities. Holter monitor is an expert's choice in detecting silent heart attacks. 

VEST device can catch heart attack signals that are too short for Holter monitor, it is beneficial in identifying patients that have silent ischemia. This test use is limited.

Difference in silent and pain-induced heart attack

• A heart attack that shows symptoms of chest pain generally occurs during a heavy activity at high heartbeat rates, whereas SMI occurs during normal activity, at low heartbeat rates
• SMI are more prominent in dawn or morning

Angina stays for just minutes while SMI can stay for hours. Many theories were proposed to explain this. In a theory called intense theory, high-intensity results in pain, while low intensity is silent. In other studies, silent attacks were found to be of less period than angina.

Mechanism of silent heart attack

SMI occurs because of obstruction in the arterial region of the heart, in the form of deposition of cholesterol on the walls, inadequate oxygen, and blood flow to the heart without resulting in any noticeable symptoms. The most common causes of heart attack include atherosclerotic plaque rupture (which causes serious injury to the affected area), sudden narrowing of the artery, vasculitis, and drug use.

People having myocardial infarction show any of the following clinical signs:

• Category 1: they show no symptoms and have no prior CAD
• Category 2: they have a prior history of CAD, but no symptoms
• Category 3: people with symptoms and no symptoms CAD, they are the most common type

Consequences

Patients without prior heart disease, also showed the risk of MI if they meet 2-3 risk factors. Soon, they have a chance of developing CAD.SMI causes localised tissue damage. Although less severe than angina-induced heart attack, it enhances the risk of future MI.⁴

Risk factors have long-term effects on the heart. They increase the risk of MI, irrespective of age and gender. Hence, screening people with a history of CAD, diabetes, and hypertension is important. Early detection can improve a person's health and will help in controlling the risks of MI. Why wait for a cure, when we can prevent heart attack?

Prevention

Lifestyle modification

Risk factors related to cardiovascular diseases (CVD) can be controlled or modified by slightly changing your habits. Consuming healthy food, enrolling in physical activity, quitting smoking & alcohol, and managing stress show a positive and long-term effect in decreasing the risk of CAD. 

Lifestyle changes impact multiple health problems at the same time, which act as risk factors for developing heart disease. They also enhance the efficacy of medical interventions or can reduce the dependency on them.

Diets

Foods enriched with vegetables, fruits, and minerals, and low levels of sugar and sodium help in lowering cholesterol levels, which when excess in the body form plaque, a major risk factor for stroke. A healthy diet also helps in maintaining a healthy weight.

There are different types of diets that you can include in your food habits.

• Mediterranean diet
• DASH (Dietary approaches to stop hypertension)
• Plant-based diet
• Anti-oxidant foods

Physical activity

Physical activity includes a wide range of exercises that can be performed by people of any age, ranging from easy to intense activity. It includes brisk walking, jogging, aerobics, Zumba, cycling, and dancing. They improve blood flow, reduce cholesterol, control blood pressure, and improve mood and insulin resistance. As a result, the chances of strokes, hypertension, and diabetes are reduced. 

Stress management

Stress leads to a lot of health problems, and CAD is one of them. It impacts sleep, and changes platelet formation, therefore controlling stress is important. Chronic stress also develops depression, anxiety, and negative emotions in people, making them socially isolated.⁵ Stress management techniques are proven to help people in need. 

Medical intervention

Treatment used for painful heart attack is also effective in treating silent heart attack.

Medicine

• Beta-blockers are the first choice medicine that reduces the number and duration of infractions
• Calcium channel blockers (CCB) are another common medicine. Aspirin is used in anti-platelet therapy and statins a lipid-lowering agent are used

Revascularization

Revascularization is a treatment that restores the normal blood flow in the body. It is only done when the person needs immediate treatment. In a study, there were no major differences between medicine and revascularization treatment, but more data is needed.⁴

Summary

A silent heart arrest happens when an obstruction in the heart stops proper blood flow in arteries. It does not show symptoms and, therefore, is unnoticeable most of the time, which unfortunately results in sudden death. People AMAB are more inclined to MI but people AFAB are more at threat. There are some atypical symptoms like sleep disturbance, pain in the jaw and neck region, nausea, and shortness of breath in the latter, but it is generally ignored by them. Several risk factors increase the chance of myocardial infarction in people who have prior CAD and those who do not have any previous heart issues. The most dangerous risk factors are type 2 diabetes, hypertension, high cholesterol, and stress. Some diagnostic tests can detect silent heart disease in a short time. Silent MI is different from generally known heart attacks in showcasing symptoms, the latter is associated with angina pain. Early detection is crucial to prevent serious problems that most times result in death. Lifestyle modification is a great preventive measure everyone should follow. A healthy diet rich in minerals and nutrients and a large range of physical activity are proven beneficial in preventing risk factors simultaneously. Some medicines are used in patients who had a previous episode of heart attack; in people with immediate intervention, surgeries are performed. One of the major risk factors is stress, which should be controlled using various stress management techniques or consulting a doctor.

To reduce the chances of heart attack, regular checkups, proper diagnosis, and physical and mental fitness are crucial.