Silent Heart Attack
Heart Attack but No Symptoms
We all think of a heart attack presenting in a typical manner – the crushing chest pain, severe shortness of breath, dizziness and excessive sweating. These symptoms arise suddenly and are unmistakably due to a heart attack. The first warning signs can help us seek emergency medical attention much earlier thereby improving the chance of survival. However, the situation is not always as straightforward. Imagine having a heart attack and not even knowing it. No typical acute episode where you are grasping your chest and fall to the floor with people scrambling around to get you to the ER. It is possible. In fact in the elderly, it is more common and twice as likely to lead to death than a heart attack with symptom . It is a silent heart attack!
Meaning of a Silent Heart Attack
The term ‘silent’ when used in medicine means a condition that is asymptomatic or minimally symptomatic. This simply means that the typical symptoms associated with certain diseases are not present or are atypical that it goes by unnoticed. A silent heart attack is damage and death of a portion of the heart muscle without the typical heart attack symptoms. Sometimes the symptoms are so mild and vague that it is confused with other conditions like acid reflux (gastroesophageal reflux disease) where stomach acid rises into the esophagus to cause heartburn. The preferred term for a silent heart attack is an unrecognized heart attack. This means that even if you did experience symptoms during the event, you did not recognize it as being due to a heart attack.
How common is it?
Heart attacks are more likely after the age of 45 years and is most common after the age of 60 years. This does not mean it cannot occur in younger adults and even adolescents or children but it is much less likely in these age groups. Silent heart attacks have found to be much more common than previously thought. It is more likely to occur in people over the age of 65 years. According to the National Institutes of Health, silent heart attacks are common as a study in Iceland revealed that up to 21% of diabetic patients and 14% of non-diabetics between 67 to 93 years had silent heart attacks. It was much higher than recognized heart attacks which occurred in 11% of diabetics and 9% of non-diabetics. Overall it is now estimated that 25% of heart attacks are unrecognized.
Why does a heart attack occur?
It is important to understand how heart attacks occur irrespective of whether it is silent or recognized. The heart has thick muscle walls which are constantly contracting and relaxing throughout life. We know this action to be the beating of the heat. It pushes out blood when it contracts and fills up with blood when it relaxes. Essentially it is the pump-action of the heart which circulates blood throughout the body. For this hardworking heart muscle to survive, it also needs a good flow of blood which can ensure a constant supply of nutrients and oxygen. The heart wall, and particularly the middle muscle layer of the wall known as the myocardium, receives this blood through the coronary arteries.
A heart attack, known medically as a myocardial infarction, tends to occur in the backdrop of coronary artery disease (CAD). This is a condition where the coronary arteries become narrowed by the build up of fatty plaques in the artery wall (atherosclerosis). It may not lead to any symptoms unless the heart needs more blood during periods of greater activity, like when exercising. However, when this narrowed artery is almost fully blocked with a blood clot then the heart muscle is starved of oxygen. Initially it leads to damage of the heart muscle known as myocardial ischemia. But when sustained and severe, a portion of the heart muscle dies (infarction).
It can also occur if the blood flow throughout the body is inadequate or there is insufficient oxygenation of the blood through breathing. However, coronary artery disease (CAD) still remains the most common cause globally.
Warning Signs and Symptoms
The very fact that an unrecognized heart attack is known as a silent attack is because it is asymptomatic. But not entirely. Some people have vague or mild symptoms and many have warning signs that were often ignored. In fact sometimes the only symptoms that are seen for months thereafter are actually heart attack complications such as irregular heartbeat, pericarditis, heart failure and so on.. The typical clutching at the chest, the crushing or squeezing chest pain. excessive sweating and dizziness that strike almost all at one may be clearly evident in a recognized heart attack but the situation is much less obvious in a silent heart attack. Nevertheless here are some symptoms and warning signs that should serve as an indicator of a possible silent heart attack.
Although the central chest pain may not be present or at least not prominent, this does not mean that there is no pain in a silent heart attack. Instead the pain may be felt at unusual locations. It is actually sites where cardiac pain is referred to such as the upper middle part of the abdomen (epigastrium), back and jaw. There may also be arm pain which is often seen as a more characteristic symptom of a recognized heart attack especially when it is left sided. Diabetics may be less likely to experience the typical pain as long term poorly controlled diabetes mellitus can damage nerves and impair the pain sensation.
Heartburn is burning sensation or pain in the chest originating from the esophagus (foodpipe). It is a consequence of stomach acid rising into the esophagus. Sometimes this burning chest pain can actually be a symptom of a heart attack. Due to common nerves to this area, heart pain and esophageal pain are often confused. Although ischemic cardiac pain is typically described as crushing or squeezing pain, any presenting symptoms in a silent heart attack are usually atypical. Persistent or recurrent heartburn that does not respond to antacids and acid-suppressing drugs may in fact be a heart attack. Often nausea is also present and the two symptoms are attributed to indigestion.
Fatigue is one of the most prominent symptoms in a silent heart attack that is often ignored or passed off for other reasons. Fatigue is not just about feeling very tired. It is about feeling tired all or at least most of the time despite having rested or waking up from a good night’s sleep. Fatigue in a heart attack is a consequence of the heart not being able to pump as efficiently as it could. Even light physical activity can cause severe tiredness that does not correlate with the level of activity. The fatigue though is usually constant and worsens with physical activity. It is also confused with malaise – a feeling of being unwell without specific symptoms. Not surprising then that many people who suffer a silent heart attack think that they have a bout of the flu without the other flu symptoms.
Being short of breath after running up a flight of stairs may not be considered abnormal especially in a person who is unfit. But being short of breath all of the time and experiencing severe breathlessness with even slight physical activity may be a sign of a diseased heart. If the heart cannot circulate oxygenated blood efficiently there is a feeling of being short of breath and the brain centers trigger the lungs to work harder. The degree of breathless often correlates with the severity of the heart attack. It may be described in many ways – difficulty breathing, out of breath or labored breathing – but is ultimately due to the underlying heart attack.
Feeling lightheaded or dizzy even without other symptoms can be symptom of a heart attack. As the heart is unable to pump as efficiently and the blood pressure may drop, reduced oxygen supply to the brain leads to dizziness. While the odd short-lived bout of dizziness may occur every now and then, persistent dizziness and severe dizziness that can even progress to fainting spells are not normal. Certain parts of the nervous system may become overactive in response to a heart attack can also cause dizziness, often with sweating. These may be the only symptoms present even with a lack of any type of pain or barely noticeable shortness of breath.
Silent Heart Attacks in Women
A heart attack can affect any gender but before the age of 70 years, men are usually more likely to develop a recognized heart attack. Most of the typical heart attack symptoms are present and medical attention is sought immediately thereby reducing the chance of death. Women in their reproductive years are protected to some degree against narrowing of the arteries due to higher circulating levels of estrogen. However, the picture changes significantly as a woman enters menopause and especially after menopause. In fact women are more likely than men to suffer with a silent heart attack and are therefore more likely to die from a heart attack.
Even when mild symptoms are present, many women tend to ignore it as they have a misconception that it is not as likely among females. There is the idea that conditions like breast cancer is more of a concern to women as heart attacks are to men. However, this is untrue. A woman is six times more likely to have a heart attack than develop breast cancer. Heart attacks kill more women every year than breast cancer. Social factors like preoccupation with caring for the family and fear are some of the other reasons why women do not seek early medical attention despite experiencing mild symptoms. Postmenopausal women with some of the symptoms mentioned above, irrespective of how mild it may be, and with risk factors like a family history of heart disease should seek immediate medical attention.