Blood Tests Predict Risk of Sudden Cardiac Death

A simple blood test can predict a person's risk for sudden cardiac death, enabling physicians to quickly and accurately assess a patient's need for an implantable cardiac defibrillator (ICD).

Current risk stratification for heart failure using markers such as left ventricular ejection fraction alone is suboptimal, and it is believed that approximately 60% of patients who receive defibrillators as a result of these assessments may not actually need one. The blood test would determine more accurately which patients do in fact need the defibrillator.

A team of scientists at the University of Illinois at Chicago (IL, USA) conducted a cross–sectional comparison trial on four cohorts composed of adult patients age 18 years or older with systolic heart failure. Control patients were defined by normal left ventricular systolic and diastolic function by echocardiographic assessment.

Blood samples were collected and were stored for up to three days at room temperature or five days at 2 °C to 8 °C. Total ribonucleic acid (RNA) was isolated using the PAXgene Blood RNA isolation kit and then converted to complementary DNA (cDNA) using the High Capacity cDNA Reverse Transcription Kit (Qiagen; Valencia, CA, USA). Total RNA was isolated from white blood cells (WBCs) and human heart tissue with Qiagen’s RNeasy Mini and RNeasy Lipid Tissue Mini Kits, respectively and then converted to cDNA using their High Capacity cDNA Reverse Transcription Kit. Only samples with an optical density (OD) 260/280 greater than 1.8, an OD 260/230 greater than 1.5, and total RNA greater than 6 μg were used. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was performed to detect the abundance of sodium channel, voltage-gated, type V, alpha subunit (SCN5A) variants.

Myocardial tissue-derived SCN5A variant expression levels strongly correlated with circulating WBC samples for both VC and VD variants. After controlling for covariates, heart failure (HF) patients who had received an appropriate ICD intervention had significantly higher expression levels of both WBC-derived SCN5A variants compared to HF patients with implantable cardioverter-defibrillators (ICDs). Receiver operating characteristics analysis revealed that circulating SCN5A variants levels were highly associated with the risk for appropriate ICD intervention.

Samuel C. Dudley, MD, PhD, chief of cardiology at the Cardiovascular Institute (Providence, RI, USA), and a senior author of the study said, “This is the first test of its kind; never before have clinicians been able to accurately assess a patient's risk of sudden cardiac death by performing a blood test. With this blood test, we can refine the need for such a device, as an ICD and instead implant the cardiac defibrillators only in the most severe cases of sudden cardiac death risk.”

Related Links:
University of Illinois at Chicago
Qiagen
Cardiovascular Institute