What is a silent heart attack?
Silent heart attack is one in which the person does not know that heart attack has occurred. This can be because chest pain was not felt or was only mild. It can also be missed if the person was under sedation or under general anaesthesia when it occurred. Earlier community studies in which ECG was recorded every two years, it was shown that up to one fourth of the previous heart attacks detected on ECG were silent. Silent heart attacks are more likely in those with diabetes mellitus (disease in which blood sugar control is abnormal and have high blood sugars without treatment). Long standing diabetes affects the nerves of the heart so that they may not feel the chest pain which common with a heart attack. Sometimes they come later with breathlessness which occurs when there is heart failure as consequence of undetected and untreated heart attack.
Though ECG studies showed one fourth as silent heart attacks, studies of high risk patients undergoing surgery under anaesthesia have shown that even half of the heart attacks in this situation can be silent. The detection rate of heart attack in this setting is higher because along with ECG, troponin estimation is also done to detect even smaller heart attacks which may be missed by an ECG. Another reason is that they are frequently given medications for pain which may cause the heart attack to be silent.
Is silent heart attack advantageous to the person as no pain is felt?
It is a disadvantage than an advantage though one does not have to suffer pain. Pain is a warning symptoms which allows to take care and medical attention. Those who do not recognize the heart attack due to lack of pain will not take rest or get medical attention and thereby miss on secondary preventive measures. So the outcome may even be worse than a symptomatic heart attack. They often present later with heart failure due to reduced pump function of the heart. Few of the lucky ones do not have any symptoms or worsening and they are incidentally detected later during some screening program or routine medical check up.