Cambridge Heart, an American company established in 1992, has designed a new test system to identify certain patients at risk for sudden life threatening arrhythmia or cardiac arrest and resultant cardiac death (SCD). The United States Food & Drug Administration (FDA) has given the company clearance to market its non-invasive cardiac diagnostic test, called Alternans Test. Cardiac arrest incidents are responsible for more than 300.000 lives a year in the United States and as such the number one cause of death. The Alternans system works like a "super stress test", that measures extremely subtle beat-to-beat fluctuations in a person's heartbeat, referred to as T-wave alternans.
Patients considered at risk for heart disease currently go through a series of non-invasive exercise stress tests that can identify ischemic heart disease, known as the clogging or narrowing of arteries. These systems don't however detect the sensitivity to arrhythmia. As a result only a small fraction of patients at risk for ventricular arrhythmia, including those with a serious, documented heart condition presently receives the definitive invasive electro-physiology (EP) testing and goes on to preventative treatment. The lack of an effective non-invasive test to evaluate the millions of patients at risk for SCD has slowed the delivery of potentially life-saving therapies.
By recognizing the presence of T-wave alternans, Alternans Test constitutes the first non-invasive diagnostic tool, able to stratify patients at elevated risk for life-threatening arrhythmia. The procedure can be easily conducted in a physician's office or a hospital stress laboratory. In fact, T-wave alternans is not visible on electrocardiograms used in conjunction with ordinary exercise stress tests. These tiny heartbeat variations, measured at one millionth of a volt, are detected during a typical treadmill or bicycle exercise stress test by specially designed, high-resolution electrodes, that are placed on a patient's chest. Extensive clinical research has shown that those patients who either show symptoms of or are at risk of life threatening arrhythmia and who test positive for T-wave alternans, are at a significant risk for subsequent sudden cardiac events including sudden death.
Currently, ventricular arrhythmia in high-risk patients is evaluated via the EP test. The EP test is a one to three hour procedure in which pace-making catheters are threaded into a major artery, typically the femoral artery in the groin, and then into the heart. Tens of millions of Americans are at risk for sudden cardiac death and over nine million have the traditional stress test. However, due to the inability of the current non-invasive tests to detect risk of ventricular arrhythmia, and the risks and costs which are associated with invasive testing, only approximately 70.000 high-risk individuals are referred for diagnostic EP testing every year.
The post-diagnosis treatment protocol for the many patients at elevated risk for ventricular arrhythmia can start with a regimen of anti-arrhythmic drugs or beta blockers, in order to treat underlying heart disease. For the highest risk patients, the preferred treatment modality is the surgical placement of an implantable cardioverter defibrillator (ICD) that automatically defibrillates the heart back into normal rhythm. The Alternans test may be used to help stratify patients whom the clinicians know or suspect are at elevated risk for SCD. This includes patients with a prior history of arrhythmia, who present with symptoms such as palpitations, syncope (fainting), light headedness or who have other specific conditions placing them at increased risk.
The Alternans "super stress test" is a fully featured diagnostic system, which includes a cart-mounted computer with proprietary software, integral ECG system, a display, a keyboard, and output devices that can be configured for both hospital and office settings. The system is developed to support a broad range of standard and physician-customized protocols for the conduct of cardiac stress tests. Alternans is compatible with either the standard electrodes or the Cambridge Heart's Hi-resolution electrodes for the detection of T-wave alternans. The system is able to control both treadmill and bicycle ergometers, devices used to exercise the patient during the test.
Starting at under $30.000 the system is just marginally more expensive than standard stress test systems. A stress test with the Cambridge Heart's test, applying T-wave alternans technology will cost about $350 per procedure on average. Incrementally, the test is expected to cost some $100 more than the traditional exercise stress test. Cambridge Heart is engaged in the research, design, and commercialization of products for the non-invasive diagnosis of cardiac disease. Using innovative technologies, the company is addressing such key problems in cardiac diagnosis as the identification of those at risk of sudden cardiac arrest, the early detection of coronary artery disease, and the prompt and accurate diagnosis of heart attack.