Warning symptoms, notably chest pain and dyspnea, occur during the 4 weeks preceding sudden cardiac arrest (SCA) in at least half of cases involving middle-aged adults, suggests a new study. The warnings are usually ignored, observe researchers, with few patients phoning 911 in response to what is almost always a fatal event.
The analysis is based on the Oregon Sudden Unexpected Death (SUD) cohort which was published online December 22, 2015 in the Annals of Internal Medicine.
It suggests that sudden death may not be as sudden as we have been thinking till now. There were people who had their symptoms not only in the 24 hours that preceded the arrest, but also in the 4 weeks that preceded their event.
The Oregon SUD study is a large, prospective, community-based study of deceased and surviving patients who had an SCA in the Portland, Oregon metropolitan area. The analysis included 839 patients between 35 and 65 years of age with SCA whose prodromal symptoms could be comprehensively assessed.
Of the 839 patients, 430 patients or 51% of the cohort experienced at least one symptom within the 4 weeks preceding their arrest. Men and women experienced prodromal symptoms with equal frequency at 50% vs 53%, respectively.
Symptoms also started more than an hour before SCA onset in 80% of patients; but in 147 of these patients, symptom onset occurred more than 24 hours before their arrest. Among this subgroup of patients, 93% had recurrent new episodes of symptoms during the 24 hours preceding their arrest.
“The main symptom was chest pain, documented in 199 patients,” or 46%, Marijon observed. Of those, 76% had “intermittent typical angina,” he said.
Another 18% of patients had dyspnea as their apparent prodromal symptom; about one-third of this group had established congestive heart failure or a pulmonary condition.
What Can Be Done
An early call to 911 was associated with better survival odds in the current study suggesting that there is a potential to enhance short-term prevention of SCA by targeting public awareness of SCA.
What is the difference between Sudden Cardiac Arrest (SCA) and Heart Attack?
ANS: Heart attack damages the heart while SCA stops the heart.
Heart attack is caused by blockages in the blood supply (coronary arteries) of the heart. The patient complains of acute severe chest pain at rest. In some patients, it may be associated with vomiting, fatigue, breathlessness, sweating and also pain in the arms.
Sudden Cardiac Arrest is caused by sudden electrical disturbance of the heart. This is mostly caused by ventricular tachyarrhythmias, (wherein the lower chambers of the heart beat so fast that there is no effective output of blood from the heart) or by cardiac standstill (no effective heart rhythm). This causes loss of consciousness with brain death ensuing in the next 4 minutes, causing eventual death.
Who is at risk of SCA?
ANS: Patients with prior heart attacks are the most at risk of SCA. 80-85% of the patients who have SCA have coronary artery disease. Majority of the patients have poor heart pumping function which is called as ejection fraction. The ejection fraction of the heart gives an idea about the output of the heart. Normally ejection fraction is in the range of 55 to 70%, however, patients with most risk of SCA have ejection fraction less than 35%.
Other patients who are more at risk of developing SCA are patients with dilated hearts and electrical disturbances of the heart.
How to respond to SCA?
ANS: Death can ensue within minutes of SCA and so prompt CPR (cardiopulmonary resuscitation) is absolutely necessary. Along with it, the patients needs to be electrically shocked (defibrillated) with the help of AED (Automatic External Defibrillator). AED are installed in most of the public utility buildings in most of the western countries and also available with all the ambulance services. The AED promptly detects the abnormal rhythm of the heart and can shock the patient out of it. However, in India, due to the dearth of trained ambulance personel, lack of AED in public places and also not much of awareness about CPR, the outlook for these patients is dismal. Only 5% of the patients are revived successfully and taken to the hospital. A practical step would be to call a doctor or an ambulance immediately.
How to prevent SCA?
ANS: Patients with prior heart attacks are the most prone for SCA. Though the patient may have undergone angioplasty or bypass grafting to restore the blood supply to their hearts, they are still at risk if the ejection fraction is less than 35%. These patients need to be evaluated by a Cardiologist, preferably a Cardiac Electrophysiologist, to ascertain their risk to develop SCA. Patients with history of prior syncope (loss of consciousness) and history of early deaths due to SCA may need thorough testing.
The basic investigation required is the 2D-echocardiography to ascertain one’s ejection fraction. Patients with low ejection fraction need to be started on medications to reduce their risks of SCA. Some patients need an electrophysiology study (EP study) to study their risk of develop SCA. EP study is a simple procedure in which 3 to 4 wires are placed in the heart via the groin to study the susceptibility to develop SCA. ICDs (implantable cardiac cardioverter defibrillators) are implanted in patients with high risk of SCA. ICDs are small devices which are implanted in the chest. These devices monitor one’s heart rhythm all the time and deliver a small shock in case the dangerous rhythm develops. ICDs are life saving devices, but cost around 4 to 8 lacs depending on the type of device used. They are proven to treat these dangerous rhythms successfully and reduce chances of dying due to SCA by 25 to 35%. There are also non-invasive electrocardiography investigations like 24 hours ECG recording, Treadmill test and ECGs with special markers to detect T-wave alternans, Heart rate variability and Late potentials. All of these investigations are now available at Hinduja Hospital.