Asymptomatic left ventricular dysfunction : Study uses AI to create early detector of heart disease

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As heart failure (HF)‐associated morbidity and mortality continue to escalate, enhanced focus on prevention is increasingly important.

“Malignant” left ventricular (LV) hypertrophy (LVH): LVH combined with an elevated cardiac biomarker reflecting either injury (high‐sensitivity cardiac troponin T), or strain (amino‐terminal pro‐B‐type natriuretic peptide) has predicted accelerated progression to HF.

We sought to determine whether malignant LVH identified community‐dwelling adults initially free of cardiovascular disease at high risk of asymptomatic decline in LV ejection fraction or a clinical cardiovascular event.

Clinical Perspective

What Is New?
  • Patients with “malignant” left ventricular hypertrophy (LVH), defined as LVH accompanied by elevations in high‐sensitivity cardiac troponin T or amino‐terminal pro‐B‐type natriuretic peptide, are at higher risk to develop asymptomatic left ventricular dysfunction and heart failure while having increased cardiovascular mortality.
  • Malignant LVH portends a significantly higher risk of developing heart failure with reduced ejection fraction in comparison with heart failure with preserved ejection fraction.
  • Malignant LVH patients who are male, as well as those with elevations in both high‐sensitivity cardiac troponin T and amino‐terminal pro‐B‐type natriuretic peptide, are at especially high risk for incident heart failure.
What Are the Clinical Implications?
  • Our study identifies a cohort of asymptomatic patients, previously free of cardiovascular disease, who are at high risk of development of heart failure and coincident adverse outcomes.
  • Patients who have been incidentally discovered to have malignant LVH may benefit from enhanced surveillance and more‐aggressive therapy.
  • Consideration should be given for screening for malignant LVH in order to prevent incident heart failure and associated morbidity and mortality.

Introduction

As the population continues to age, increasingly the first episode of symptomatic cardiovascular disease (CVD) manifests in the form of heart failure (HF).1 For the primary prevention of HF, there are challenges in the identification of novel risk factors outside the “traditional” factors that also apply to atherosclerotic disease, attributed to the heterogeneous nature of HF progression among asymptomatic individuals.

However, preliminary evidence suggests that a multimodality cardiac‐specific biomarker approach has potential to differentiate risk beyond traditional risk factors or a single modality, such as imaging or blood tests alone.2

Left ventricular (LV) hypertrophy (LVH) is determined by noninvasive measurement by multiple modalities. Whereas patients with LVH represent a risk group for adverse outcomes, progression to reduced LV systolic function, let alone major adverse cardiac events, occurs in a minority.3 

Recent studies by our group have demonstrated that presence of LVH in conjunction with elevated soluble biomarkers for myocardial injury (high‐sensitivity cardiac troponin T; hs‐cTnT) and hemodynamic stress (amino‐terminal pro‐B‐type natriuretic peptide; NT‐proBNP) can identify a “malignant” phenotype of LVH more likely to progress to HF or death in both middle‐aged and older individuals

A Mayo Clinic study finds that applying artificial intelligence (AI) to a widely available, inexpensive test—the electrocardiogram (EKG) – results in a simple, affordable early indicator of asymptomatic left ventricular dysfunction, which is a precursor to heart failure.

The research team found that the AI/EKG test accuracy compares favorably with other common screening tests, such as mammography for breast cancer.

The findings were published in Nature Medicine.

Asymptomatic left ventricular dysfunction is characterized by the presence of a weak heart pump with a risk of overt heart failure.

It affects 7 million Americans, and is associated with reduced quality of life and longevity. But asymptomatic left ventricular dysfunction is treatable when identified.

However, there is no inexpensive, noninvasive, painless screening tool for asymptomatic left ventricular dysfunction available for diagnostic use.

The Mayo study reports that the best existing screening test for asymptomatic left ventricular dysfunction is to measure natriuretic peptide levels (BNP), but results of BNP have been disappointing.

And the test requires blood draws.

Left ventricular dysfunction typically is diagnosed with expensive and less accessible imaging tests, such as echocardiograms, or CT or MRI scans.

“Congestive heart failure afflicts more than 5 million people and consumes more than $30 billion in health care expenditures in the U.S. alone,” says Paul Friedman, M.D., senior author and chair of the Midwest Department of Cardiovascular Medicine at Mayo Clinic. “The ability to acquire an ubiquitous, easily accessible, inexpensive recording in 10 seconds—the EKG—and to digitally process it with AI to extract new information about previously hidden heart disease holds great promise for saving lives and improving health,” he says.

In their study, Mayo Clinic researchers hypothesized that asymptomatic left ventricular dysfunction could be reliably detected in the EKG by a properly trained neural network. Using Mayo Clinic stored digital data, 625,326 paired EKG and transthoracic echocardiograms were screened to identify the population to be studied for analysis. To test their hypothesis, researchers created, trained, validated and then tested a neural network.

The study concluded that AI applied to a standard EKG reliably detects asymptomatic left ventricular dysfunction. The accuracy of the AI/EKG test compares favorably with other common screening tests, such as prostate-specific antigen for prostate cancer, mammography for breast cancer and cervical cytology for cervical cancer.

In addition, in patients without ventricular dysfunction, those with a positive AI screen were at four times the risk of developing future ventricular dysfunction, compared with those with a negative screen. “In other words, the test not only identified asymptomatic disease, but also predicted risk of future disease, presumably by identifying very early, subtle EKG changes that occur before heart muscle weakness,” notes Dr. Friedman.
More information: Screening for cardiac contractile dysfunction using an artificial intelligence–enabled electrocardiogram, Nature Medicine(2019). www.nature.com/articles/s41591-018-0240-2
Provided by Mayo Clinic

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