Johns Hopkins Medical Study: Abnormal Heart Metabolism Could Predict Future Sudden Heart Death

The findings were published June 22 in JCI Insight.

“We believe this is the first time that impaired cardiac metabolism in people has been associated with an increased risk of life-threatening arrhythmias or sudden cardiac death,” said study senior author Robert Weiss, MD, professor of medicine at Johns Hopkins University School. Medical. “This could open a window for an entirely new approach, a metabolic approach to treat or prevent severe arrhythmias, which are not currently available in cardiology.”

Sudden cardiac death accounts for 50% of all cardiovascular deaths in the United States, claiming more than 300,000 American lives each year, according to the American Heart Association. Currently, an implantable cardioverter-defibrillator (ICD) – a small, battery-powered device that is placed in the chest to detect and stop irregular heart rhythms – is the main way to prevent SCD in high-risk patients. The device continuously monitors the heart rhythm and delivers electric shocks, when needed, to restore a regular heart rhythm. ICD battery life is usually between five and seven years.

“Over seven years, 60%-70% of these devices are never removed to save lives,” says T. Jake Samuel, Ph.D., study first author and associate in cardiology at Johns Hopkins Medicine. “We spend billions of dollars a year on implanted ICDs and they have both procedural and post-procedural risks. There is a need for a non-invasive approach to better assess risk for those who need or do not need an ICD to prevent sudden cardiac death in humans.”

For their study, Samuel and colleagues measured the levels of adenosine triphosphate (ATP), the main chemical cellular energy source, in the livers of 46 people before getting ICD for primary prevention. Cardiac ATP levels were measured on a clinical magnetic resonance imaging (MRI) scanner using a magnetic resonance spectroscopy (MRS) technique developed at Johns Hopkins Medicine by Paul Bottomley, Ph. abnormal. All patients were followed up every three to six months for a median of 10 years to determine which patients had an appropriate ICD for life-threatening arrhythmias.

Results showed that people with low cardiac ATP levels (metabolic disorders) had a threefold higher risk of sudden cardiac death (if not rescued by ICD intervention) compared to those with normal ATP metabolism. This was still the case when adjusting for low left ventricular ejection fraction, a metric currently used to determine the need for primary preventive ICDs.

“ICD was never required in about 80% of those with normal cardiac ATP levels at 10 years during the study period,” Samuel and colleagues report. They say the study’s findings could complement current approaches and lead to better predictions as to who is most likely to need, or not need, an ICD. However, they emphasize, that more research is needed to assess different and larger populations.

“But we’re excited about these completely new findings, arguably the first in humans, and believe they can change the way doctors assess the risk of sudden cardiac death,” Weiss said. “Once we have confirmed that metabolism and SCD are linked, we hope to study which drugs maintain and enhance ATP metabolism, and whether they can be used to reduce the risk of SCD.”

In addition to Weiss, other researchers include T. Jake Samuel, Michael Schär, Katherine Wu, Angela Steinberg, Mark Anderson, Gary Gerstenblith and Paul Bottomley of Johns Hopkins University School of Medicine; An-Chi Wei of National Taiwan University in Taipei, Taiwan; and Gordon Tomaselli of the Albert Einstein College of Medicine in the Bronx, New York.

No conflicts of interest to report.

This research was supported by the DW Reynolds Foundation, NIH (grant HL61912, HL056882, HL103812, HL132181, HL140034) and the Russell H. Morgan and Clarence Doodeman endowment at Johns Hopkins

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