A blood test can predict who would benefit from Implantable Cardioverter Defibrillators (ICD), which are surgically implanted in heart failure patients to prevent sudden death,
The straightforward laboratory test can tell with high accuracy which patients will or will not require an ICD for the next 12 months that would prevent arrhythmia and its subsequent cardiac arrest.
Physicians at the Chicago College of Medicine (IL, USA) carried out a clinical trial on 180 adults participants of whom 135 of them had heart failure, and 45 were healthy individuals as the control group. They excluded people with inflammatory conditions, infections, and congenital heart disease. The blood test, called PulsePredic, detects alterations in the messenger ribonucleic acid (mRNA) for the sodium channel, voltage-gated, type V, alpha subunit (SCN5A) gene, which previous studies have shown to be closely linked with sudden death. The increase in the altered mRNA was found to be a good predictor of which patients were most likely to have a sudden death episode requiring defibrillation.
The scientists measured the SCN5A gene in white blood cells and heart muscle cells. By analyzing the alterations in the mRNA, they could predict who would have a sudden death episode where defibrillation would be required. The patients with heart failure who had arrhythmias that would cause sudden death were found to have considerably higher levels of these genetic mutations, compared to those with normal heartbeats. By measuring variant levels in the blood, they were able to predict surprisingly accurately who had arrhythmic risk, suggesting that it is possible to have a blood test for sudden death risk and the need for an ICD.
Certain proteins, called voltage-gated sodium channels, are responsible for generating the main current for the electrical signals in the heart. The SCN5A gene encodes for these proteins. Arrhythmias occur when there are rises or falls in the sodium current. Samuel C. Dudley, MD, PhD, chief cardiologist at the University of Illinois (Chicago, IL, USA), explained, “The test predicts whether you will have sudden death from heart failure and whether you will need a defibrillator in the next year." Professor Dudley is the CEO of ROS Technologies, Inc., the university’s spinoff company that will develop the blood test. The study was presented at the European Society of Cardiology Congress 2012, held in Munich (Germany).