Photo: Sebastian Gray
It’s the only known condition that kills 90 percent of its victims within 10 minutes. And predicting it is just as perplexing to cardiologists as forecasting the perfect storm is to meteorologists. But what if we could identify symptoms of sudden cardiac arrest as early as four weeks prior to the deadly event? Would it make a difference in saving lives? Investigators at the Cedars-Sinai Heart Institute say “yes,” and they can prove it.
In a landmark discovery, published in January 2016 in the Annals of Internal Medicine, investigators showed that more than 50 percent of patients experience warning symptoms up to a month before suffering a sudden cardiac arrest — a deadly condition that, until now, seemed to strike without warning. Unfortunately, most of those affected will ignore those symptoms and essentially lose any chance at lifesaving medical intervention.
“This is a major paradigm shift in cardiology,” says Sumeet S. Chugh, MD, medical director of the Heart Rhythm Center in the Cedars-Sinai Heart Institute and the Pauline and Harold Price Chair in Cardiac Electrophysiology Research. “Earlier on, our focus was only on the immediate time preceding cardiac arrest, and on people known to have heart disease. Now we can focus on targeted symptoms as predictors of sudden cardiac arrest, and we can potentially save many lives through earlier preventive care.”
The study, which followed 839 patients between the ages of 35 and 65, outlines the most common symptoms of sudden cardiac arrest. These include intermittent chest pain and pressure, shortness of breath, palpitations, and ongoing influenza-like indicators such as nausea and abdominal and back pain.
“This is pretty exciting research, given that we are that much closer to solving the riddle of predicting cardiac arrest in people, especially those who are of middle age,’’ says Eduardo Marbán, MD, PhD, director of the Cedars-Sinai Heart Institute. “The societal burden is greatest among this age group because they often leave behind widows and descendants, and if, by some miracle, they survive, they are less likely to be self-supporting.” These new findings also give good reason not to ignore unusual sensations and to seek medical attention early.
Although “heart attack” and “sudden cardiac arrest” often are used interchangeably, the terms are not synonymous. A heart attack — myocardial infarction — is typically caused by clogged coronary arteries that reduce blood flow to the heart muscle. Sudden cardiac arrest is the result of defective electrical activity of the heart that usually causes instantaneous death.
Approximately 350,000 people in the U.S. die each year from sudden cardiac arrest, accounting for 50 percent of all cardiovascular deaths nationwide. While improving survival among patients who experience sudden cardiac arrest is important, research has shown that prevention in high-risk patients has a greater impact on survivorship.
Sudden cardiac arrest is a rapid electrical short circuit of the heart, which can be reversed by a life-giving electric shock. However, life ebbs within minutes, and most victims cannot be reached in time. Predicting which heart is destined for electrical failure is one of the hottest areas in heart research today. Photo: Sebastian Gray
Pacing and rhythm-control devices, including pacemakers and implantable cardioverter defibrillators, are used to treat arrhythmias and other disturbances of the heart’s rhythm. These devices send and receive electrical signals to and from the heart to regulate heartbeat. They are lifesaving in many situations. Pictured here, the leadless pacemaker is the size of a vitamin capsule and completely self-contained within the heart — no wires required. Photo: Sebastian Gray
The surgically implantable defibrillator can function as a personal paramedic. This electrical device provides a shock that restores life within seconds, but new discoveries must identify who will benefit the most. Ongoing research at the Cedars-Sinai Heart Institute has made major contributions in this area of clinical science. Photo: Sebastian Gray
Implantable defibrillators — surgically implanted electronic devices designed to stop rapid, life-threatening heart rhythms — are long-term lifesavers for survivors and those at risk of sudden cardiac arrest. But the discovery of early warning symptoms brings potential for new, shorter-term approaches to prevention. Increasing awareness of such symptoms among patients and healthcare providers is a major step in the right direction.
“In certain cases, this will allow physicians to intervene quickly, by implanting an electrical device sooner rather than later,” says Chugh, a world-renowned authority in electrophysiology whose Arrhythmia Research Program and Laboratory at the Heart Institute focuses on identifying novel ways of predicting, treating, and preventing heart rhythm disorders.
Chugh initiated and continues to direct the Oregon Sudden Unexpected Death Study, a large, comprehensive assessment of sudden cardiac arrest that’s been conducted for more than 13 years in a community of 1 million residents. In February 2015, the study was expanded to Ventura County, California. This crucial research continues to shed light on the risk factors, triggers, and genetic defects related to sudden cardiac arrest, with the overall goal of designing novel techniques for treatment and prevention.
“The hope is to soon use these findings to develop a battery of screening tests or a checklist for physicians that will better predict who is likeliest to suffer sudden cardiac arrest,’’ he says. “When you’re trying to predict the perfect storm, being able to make that prediction as early as possible is the difference between disaster and triumph.”
51 percent of patients experienced warning symptoms, predominately chest pain, prior to the cardiac arrest. In the group that experienced symptoms, 93 percent experienced them again in the 24 hours preceding the cardiac arrest.
Only 19 percent of those who experienced symptoms called emergency medical services.
Patients who experienced symptoms and sought medical help had a survival rate of 32 percent. Those who did not seek medical treatment for symptoms had a survival rate of 6 percent.