A blood test was devised that identifies specific cells that flake off when the blood vessel walls weaken and signal the initial stages of acute myocardial infarction (MI).

The blood test that can predict whether a person is at high risk of suffering from a heart attack and can provide the doctor and patient with this vital information up to two weeks before an acute MI or cardiac episode is likely to occur.

Scientists at Scripps Translational Science Institute (La Jolla, CA, USA) enrolled patients between January 2010 and February 2011, who presented to the emergency room with ST-segment elevation MI (STEMI) at four regional medical centers and had blood drawn for circulating endothelial cells (CECs) characterization. The study involved 94 participants, 50 of them had had a heart attack while the other 44 were healthy controls. The CECs were identified using the CellTracks system, which consists of an automated CellTracks Auto Prep sample preparation device and a CellTracks Analyzer II (CTA II) image analysis platform. Fluorescence intensity measurements of fixed CECs from CellSearch were carried out in a four-step process. Total ribonucleic acids (RNAs) were isolated from CECs according to the standard TRIzol method for gene expression analysis.

The CEC blood levels among those who had had a heart attack were over four times higher when compared to those in the healthy control group. Not only CEC blood levels were much higher among the heart attack patients but also their CECs had changed; they had either become larger, misshapen, and/or many had multiple nuclei. During the initial stages of a heart attack, the walls of the blood vessel weaken, they become eroded, attracting inflammatory cells, which in turn harm and damage the endothelial cells that line the inside of blood vessels. Endothelial cells are those that form the cellular lining of a tissue. Severe inflammation causes the CECs to mutate; they clump together, break off and get into the bloodstream.

The CellSearch System used in this study is a commercially available rare cell isolation platform manufactured by Veridex (North Raritan, NJ, USA). Eric J. Topol, MD, a senior author of the study, said, "For the first time, we can isolate these cells through techniques that were not available in 1999. They are like a window into the process that underlies an imminent heart attack.” In a considerable number of cases, CECs sloughing off the interior wall of a blood vessel become involved in a series of events that results in a blood clot. Professor Topol added, "It is the clot that cuts off the blood supply and serves as the proximate cause of a heart attack. Eventually, a plaque ruptures and a blood clot develops." The study was published on March 21 2012, in the journal Science Translational Medicine.

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