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Time SCA Occurs is Changing

Time SCA Occurs is Changing

January 29, 2019 | Last Updated: July 16, 2021

How the time of SCA has shifted and the potential impact on survivability.

Could shifts in the time at which SCA occurs actually lead to more lives saved?

Sudden Cardiac Arrest (SCA) has long been viewed as a lethal medical condition most likely to occur in the morning and, more specifically, on Mondays.

According to a recent CNN article: “The dogma — in fact, this is everywhere, in all the textbooks about sudden cardiac arrest — [is that] the most common time period for people to have a sudden cardiac arrest is early in the morning,” said Dr. Sumeet Chugh, one of the authors of the study published in the journal Heart Rhythm.

Chugh et. al performed a contemporary evaluation of SCA data from the general population in a Northwestern US community of approximately 1 million people over a 12-year period, from 2002-2014.

In order to accurately estimate the time in which the SCA occurred, the study was limited to witnessed SCA, resulting in a population of 1,535 patients 18 years or older. “The specific time of each SCA event was determined based on the time of the 911 call to EMS,” according to the study.

The reported incidences of SCA occurred at the following times:

(Graph shows time of day that SCA occurs based on Dr. Chugh study)

The authors attempt to explain the change in data by citing improved reporting accuracy, treatment changes, such as new medications that could be affecting the time of SCA, and a “shift to a more 24/7 culture.”

Further, from CNN:
“Our hypothesis is that in the last decade or two decades, we’ve really changed the way that we behave as human beings. We’ve changed the way that we work. We are constantly wired,” Chugh said. “I would call it an ‘always on’ existence. A lot of people are working all the time, or they’re tied to, or tethered to, a smartphone, almost every instant of the day, sometimes at night.”

Could this change be positive?

Given that the data are shifting from peaks in the morning to more evenly distributed SCA incidents throughout the day, it’s logical to assume that more SCAs are occurring during work, school, or other hours in which potential victims are in a public setting. If so, presumably there would be more bystanders available during these windows of time than at night or early mornings and, thus, the chain-of-survival can begin sooner than in prior periods.

With more bystander responders available, greater awareness and recognition of SCA, and an increased prevalence of Automated External Defibrillators (AEDs), could it be that our recent addiction to smartphones and our shifts to a “24/7 culture” will actually improve survivability?

As the next-generation of wirelessly connected “smart AEDs” come to market, our data, treatment methods, and reporting of this enormous public health issue will only improve.