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Medscape
25-06-2025
- Health
- Medscape
Future Shock: Preventing Sudden Cardiac Death Is Possible
For patients with certain cardiovascular conditions and risk factors, sudden cardiac arrest is more than a theoretical concern. But over the past 25 years, the development of various types of defibrillators — at-home, implantable, wearable — can give the immediate shock needed if a patient at high risk goes into ventricular arrythmia. The approach is saving lives, but not enough; implantable devices have complications and most wearable devices can't be worn all the time. Stories of 'if only' tragedies abound, like that of patients who suffered sudden cardiac death while in the shower, their wearable device hanging inches away on the hook of the bathroom door. Cardiologists who study sudden cardiac death say closing the gap is possible, with attention to several critical shortcomings. Determining Risk The first, and most important, area for improvement is understanding of who is likely to experience a sudden cardiac event. About 80% of sudden cardiac arrests globally are related to coronary artery disease, said Eloi Marijon, MD, a cardiovascular and cardiac electrophysiology specialist at the European Georges Pompidou Hospital in Paris, France, who coauthored a 2023 report of a Lancet Commission calling for multidisciplinary action to reduce the global burden of sudden cardiac death. But the number of patients with the condition who eventually have an arrest is low, said Kumar Narayanan, MD, a cardiologist and electrophysiologist at Medicover Hospitals in Hyderabad, India, and a coauthor of the Lancet Commission document. 'As of now, we do not have good tools to screen and identify those people,' said Narayanan. 'We need much better prediction, which will translate to better prevention.' (A related story on Medscape Medical News looks at sudden cardiac arrest in people with no history of heart problems.) Patients with 'advanced markers of damage' — such as heart failure with reduced ejection fraction or a high fibrotic burden and certain characteristics of fibrosis — are at highest risk, he said. Acute myocardial infarction and coronary artery bypass grafting also can raise risk temporarily. In fact, risk is 'dynamic,' varying over time, he said, making predicting arrest particularly challenging. Although Narayanan calls current prediction methods 'imperfect,' known risk factors are helping cardiologists provide appropriate patients with a growing selection of devices to deliver shocks when and where an arrest occurs. Home Is Where the Heart Stops Having an automated external defibrillator (AED) at home, where most arrests happen, has been an option for patients at risk since the 1980s. But studies of home AEDs have shown mixed results. A 2013 study found the use of AEDs at home by laypeople to be safe and effective, leading to the survival of two thirds of patients who received defibrillation. But a 2008 randomized controlled study found no benefit from home AEDs over cardiopulmonary resuscitation performed by emergency medical services in high-risk patients. The value of implantable cardioverter-defibrillators (ICDs) for patients who have heart failure with reduced ejection fraction has been shown in studies since the late 1990s. Current guidelines from American and European groups recommend ICDs for the primary prevention of sudden cardiac arrest and death in these patients. In both guidelines, recommendations are class 1A, indicating strong support by high-quality evidence of a clear benefit. ICDs are usually a permanent solution, but not a perfect one, said Marijon, a cardiovascular and cardiac electrophysiology specialist at the European Georges Pompidou Hospital in Paris, France, and a coauthor of the Lancet Commission report. 'An ICD for life has a 100% chance of complications,' Marijon said. Studies show ICDs may incorrectly administer shocks when there is no arrest, and intravascular leads may fail or become infected, requiring surgical intervention. Efforts are underway to improve these devices, but industry and researchers should collaborate to develop models that protect patients yet have fewer complications, he added. Newer options for patients at high risk include cardiac resynchronization therapy, which involves the implantation of a biventricular pacemaker, and catheter ablation, which can correct certain arrythmias associated with risk for sudden cardiac arrest, although its ability to prevent arrest is unclear. Wear That Defibrillator For patients who have a transiently high risk for arrest after acute myocardial infarction or coronary artery bypass grafting or who are waiting for ICD implantation, wearable cardioverter-defibrillators are an option. LifeVest, a wearable device for sudden cardiac arrest that detects ventricular tachyarrhythmias and administers a shock to correct them, was first tested in the WEARIT and BIROAD studies, as reported in 2004. Those studies showed a beneficial effect in treating arrests. But when LifeVest was assessed in patients who had experienced a recent myocardial infarction in a 2018 major randomized controlled trial, the difference between it and regular care was not significantly different. However, a later analysis of the 2018 trial data showed that LifeVest was effective, both statistically and clinically, in patients who used it as intended. Questions of effectiveness aside, using the vest as intended has proven difficult for patients. Compliance issues have dogged the ability of wearable devices to prevent sudden cardiac arrest. 'It's the Achilles heel for all of them,' said Emile Daoud, MD, an electrophysiologist at the TriHealth Heart and Vascular Institute in Cincinnati. 'The question is not whether they work; the science of defibrillation we have figured out pretty well. Acceptance is really the problem.' False alarms, inappropriate shocks, and discomfort are frequent complaints with LifeVest, which is the only commercially available wearable cardioverter-defibrillator. New devices have been designed to improve compliance. The ASSURE wearable device has been shown to have a low rate of false alarms. Jewel, a lightweight wearable cardioverter-defibrillator, uses a patch placed over the heart and a box worn on the side of the torso to monitor cardiac activity and restore normal function. Unlike other wearable products, it can be worn in the shower and during exercise or sleep, which can improve compliance and avoid tragedies like the sudden cardiac arrest in the shower, said John Hummel, MD, an electrophysiologist at the Ohio State University Wexner Medical Center in Columbus, Ohio, who was the principal investigator for a 2024 study of the device. Next Generation Technology will help improve these devices, according to Narayanan and Marijon, and the quality of life and survival of patients at high risk. Recent advances in drug therapy for heart failure and ischemia should also help prevent sudden cardiac arrest, according to the Lancet Commission report. With aging populations and higher rates of coronary artery disease, all medical measures — better screening and diagnosis of cardiac diseases, improved treatments, more AEDs in homes and public places, and widespread use of implantable and wearable cardioverter-defibrillators — must be brought to bear, the report stated. 'We need some disruptive innovations in prediction and prevention,' said Narayanan, who points to artificial intelligence and machine learning as showing particular promise to better diagnose the underlying conditions and better predict the risk of arrest. But medical advances are not enough. The Lancet Commission report urges international research and collaboration, as well as awareness among the public and policymakers. 'Governments could do more,' said Simone Savastano, MD, a cardiologist at Fondazione IRCCS Policlinico San Matteo in Pavia, Italy. 'If you work with children or young men and women, you can raise a generation that is aware and is more keen to help a cardiac arrest patient.' Daoud reported receiving consulting fees or honoraria from Biosense-Webster, AltaThera, and OSU EP Section Educational conferences; he is the chief medical officer of S4 Medical and he has received fees from the American Board of Internal Medicine and the Journal of the American College of Cardiology. Hummelreported receiving consulting fees from Medtronic, Volta Medical, S4 Medical, Abbott Medical, and Element Science. Marijon disclosed receiving grants from Abbott, Biotronik, Boston Scientific, Medtronic, MicroPort, and Zoll; consulting fees from Medtronic, Boston Scientific, Zoll, and Abbott; and payment or honoraria for lectures, presentations, speakers' bureaus, manuscript writing, or educational events from Medtronic, Boston Scientific, Zoll, and Abbott. Narayanan and Savastano reported no relevant financial conflicts of interest.
Medscape
24-06-2025
- Health
- Medscape
Sudden Cardiac Arrest Victims Often Have No Prior Diagnosis
An apparently healthy young woman going through a typical day of university classes in Italy collapses suddenly. For many people, this medical emergency would end in tragedy. But in this case, the woman's friends retrieve an automated external defibrillator (AED) and give her the shock she needs to restore her normal heartbeat. She recovers fully, and her future looks bright. This true story is the best-case scenario for patients who experience sudden cardiac arrest, but such stories remain frustratingly rare, experts said. Between 6% and 22% of people who experience a cardiac arrest outside of a hospital survive the event, according to a 2019 study of 12 countries; the rate varies widely both between and within nations. Sudden cardiac arrest continues to account for about half of all cardiac deaths and a significant percentage of all deaths, despite advances in the identification and treatment of the underlying cardiomyopathies, arrhythmias, and coronary artery disease that can lead to cardiac arrest. About half of all arrests strike people who had no prior diagnosis of cardiac disease. Screening people for cardiac diseases, treating these conditions, and, when all else fails, resuscitating victims promptly save lives. But much more vigilance, public awareness, and research are needed, experts said. 'It's a social issue and an economic issue,' said Eloi Marijon, MD, a cardiovascular and cardiac electrophysiology specialist at the European Georges Pompidou Hospital in Paris. Marijon was a co-author of a 2023 report for a Lancet Commission that called for multidisciplinary action to reduce the global burden of sudden cardiac death. Many Causes, One Outcome 'Sudden cardiac death is a mode of death, not a disease,' Marijon said. 'But it's a unique mode of death. You are dead, but it's still reversible for a few minutes.' A variety of cardiac diseases can form the 'substrate' that leads to an arrest, said Kumar Narayanan, MD, a cardiologist and electrophysiologist at Medicover Hospitals in Hyderabad, India, and a co-author of the Lancet Commission report. A 'trigger,' such as acute ischemia, electrolyte imbalance, or drug effects, is necessary. Finally, the autonomic nervous system that normally modulates cardiac rhythm must fail. Because so many cardiac conditions can lead to arrest — conditions people may not even be aware they have — preventing and treating sudden cardiac arrest is challenging. Sudden cardiac arrest has different profiles. In people younger than 35 years, the main culprits are structural and electrical cardiac abnormalities, whereas in older people, the main cause is coronary artery disease. Yet experts say they are starting to see more arrests due to coronary artery disease in younger people. Media reports of athletes collapsing during a sport have brought attention to cardiac arrest in young people. Sudden cardiac death, while quite rare, was the most common medical cause of death among athletes aged 17-24 years who died during a wide variety of sports, according to a 2015 study of a National Collegiate Athletic Association (NCAA) database. Many of the conditions that lead to arrest in athletes younger than 35 years are inherited, said Sanjay Sharma, MD, a cardiologist at City St George's, University of London, England, and a co-author of a 2024 review of sudden cardiac deaths in young athletes. In a registry of sudden death in athletes, in which hearts were examined by a cardiac pathologist, researchers observed 'nothing wrong with the heart or coronary arteries' in many cases, Sharma reported. 'They are sudden arrhythmic deaths. Why do these happen? If we look at first-degree relatives very comprehensively, we find an inherited electrical cause in 40% of these families.' To prevent such deaths, some jurisdictions and sports associations have started to screen athletes for cardiac conditions before they participate in sports. 'Whatever we do to identify these young people, on ethical or moral grounds, it has to be easy to do and pragmatic,' Sharma said. In the US, screening consists of a physical examination and individual and family history. An ECG is recommended but not required, according to a joint scientific statement from the American Heart Association and the American College of Cardiology, because costs and rates of false-negative and false-positive results are high. In contrast, the European Society of Cardiology recommends 12-lead ECG screening. Data support that approach. In Italy, where ECG screening is mandatory, the rate of sudden cardiac death decreased from 3.6 to 0.4 per 100,000 athlete-years, according to a 2006 study. The 2015 NCAA study, by comparison, found a rate of sudden cardiac death of 1.9 cases for each 100,000 athlete-years. But no test can pick up all cases. And tests must be repeated, Sharma said. 'A one-off screen is not enough,' but the best schedule for screening — whether every year or 2 years — is unclear, he added. Furthermore, such screening can have false-positive results. For example, high-intensity exercise can cause benign changes to the heart, commonly called athlete's heart, which may point to cardiomyopathies on ECG or imaging. In some athletes, mainly men who participate in endurance sports, the dimensions of ventricles can change, whereas in other athletes, mainly Black men who play team sports, the left ventricular wall may thicken. Additional imaging and testing are required to distinguish these unharmful changes from serious cardiac conditions, he explained. For most older adults, coronary artery disease remains the main underlying cause of arrest, although estimates of rates differ. Arrests can result from heart failure or during the acute phase of a myocardial infarction. The aging of the populations in most countries means rates of sudden cardiac arrest are likely to rise. Experts agree the general cornerstones of prevention are the same as for coronary artery disease: Better screening for cardiovascular risk factors, prompt investigation of possible ischemia or heart failure, and effective therapies when disease is detected. When Arrest Occurs When sudden cardiac arrest strikes, the first minutes determine survival. Estimates put the survival rate at less than 10% without intervention. If an arrest is witnessed, the likelihood of survival doubles, Sharma said. If cardiopulmonary resuscitation (CPR) is started immediately, survival triples, and if defibrillation is administered within the first few minutes, it increases fivefold. Because of highly visible dramatic rescues and tragic but avoidable deaths, CPR and AEDs have taken center stage as tools to improve survival after a sudden cardiac arrest. However, the deployment of these methods is as much a public policy issue as a medical one. Many jurisdictions have put AEDs in sports facilities because of the well-known risk for sudden cardiac arrest in athletes. This policy is supported by studies that show that CPR and AEDs improve survival rates following arrest during exercise — from 15% to 55% in Switzerland and up to 70% in Sweden — although rates of sudden cardiac arrests are staying the same or rising. The recent RACER 2 study of marathons and half-marathons in the US showed that the rate of arrest from 2010 to 2023 was similar to that from 2000 to 2009, but the rate of sudden cardiac death was cut in half. Emergency preparedness at races improved after the 2012 RACER 1 study reported the number of sudden cardiac arrests and deaths occurring during marathons, said Jonathan Kim, MD, founding director of sports cardiology at Emory University in Atlanta. By the time RACER 2 was conducted, all racers who collapsed during the marathons assessed received CPR from bystanders, and almost all received defibrillation, leading to a dramatic decline in mortality. AEDs in public places, such as transportation stations and office buildings, are common in some jurisdictions but not in others. Monaco has defibrillators 'everywhere — you couldn't miss them,' Sharma said, whereas Kenya lacks basic equipment such as ECGs, not to mention AEDs. Officials in the Italian city of Senigallia have been installing AEDs in residential areas to improve the survival of people who experience sudden cardiac arrests at home. 'You should have an AED inside an apartment building, like a fire extinguisher,' said Simone Savastano, MD, a cardiologist at Fondazione IRCCS Policlinico San Matteo in Pavia, Italy, who helped write a 2020 literature review on the devices. 'If you have one at the entrance, everyone knows that there is an AED. In case of an emergency, they can run downstairs and use it,' Savastano said. However, placing AEDs is only a first step. Paris has numerous AEDs in public places, but 40% of them are out of service, Marijon said. 'It's good to put an AED on the wall, but you have to maintain it,' he said. AEDs should be required by law, just like fire extinguishers, Marijon and Narayanan pointed out, and good Samaritan laws that exempt bystanders who use AEDs from liability are also needed. However, an American study showed laws requiring AEDs in sports facilities do not significantly increase the number of times bystanders use an AED to treat an arrest, said author Saket Girotra, MD, SM, a cardiologist with the University of Texas Southwestern Medical Center in Dallas. 'I was surprised because I would have expected some increase in AED use in states that required them to be placed in athletic facilities,' Girotra said. Laws are not enough, he said. 'I think that is a lesson for the community and for policymakers. We need to go beyond passing these laws. We need to make sure that the people who operate the facilities are well trained and the public is informed,' Girotra said. Among the measures recommended is widespread CPR training. A successful public campaign in India involved celebrities talking about cardiac arrest and encouraging members of the public to register for CPR training, Narayanan said. American and European guidelines say every emergency medical system must create a way to alert citizens and first responders to someone having an arrest, Savastano said. Today's AEDs are foolproof. They provide automated aural instructions to the user throughout the process and a picture of where to place the pads on the patient. Sensors determine whether the patient needs a shock. 'It's impossible to use it in the wrong way,' Savastano said. For bystander intervention, smartphone apps are useful. 'In many countries, apps alert citizens in case of a cardiac arrest near them,' he said. Apps showing the locations of nearby AEDs help citizens find one and get it to the patient. 'In Switzerland, in one canton, they have been doing this for many years. They are able to reach every patient with a cardiac arrest within 3 minutes,' Savastano said. Political willingness is needed to institute CPR and AED measures. 'Politicians probably think that cardiac arrest is not a political concern,' he added. 'But it is.' Marijon disclosed receiving research funding, consulting fees, and an honorarium from a variety of medical device makers and drug companies. Kim reported receiving grant funding from the Atlanta Track Club and the National Institutes of Health (NIH). RACER2 was supported by NIH/National Heart, Lung, and Blood Institute (NHLBI) grant R01HL162712. Girotra reported receiving grants from the NHLBI and personal fees from the American Heart Association for editorial work outside the article discussed in this story.
