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CAMH News Largest Prospective Study of Microvolt T-Wave Alternans Demonstrates This Technology's Predictive Value for Sudden Cardiac Death in Patients With Preserved Left Ventricular Function After Acute Myocardial Infarction

BEDFORD, Mass.--(BUSINESS WIRE)--Cambridge Heart, Inc. (OTCBB-CAMH) announced today the publication of a study in the Journal of the American College of Cardiology assessing the utility of Microvolt T-Wave Alternans™ (MTWA) in predicting risk of sudden death among patients who have previously suffered a heart attack (Acute Myocardial Infarction; MI) yet have preserved cardiac function. This group of patients is outside of the MADIT II and SCDHeFT populations as the study included only patients with a left ventricular ejection fraction (LVEF) greater than or equal to 0.40, while the two aforementioned studies involved LVEF ≤ 0.30 and LVEF ≤ 0.35 patients respectively. The results indicate that the MTWA test, using the Cambridge Heart patented Spectral Analytic Method during low heart rate exercise, identifies those patients who are at elevated risk for sudden cardiac death and therefore may benefit from implantation of a defibrillator.

The US post-MI population consists of approximately 7,200,000 people. 565,000 new MI patients join this group annually and 225,000 die each year from another MI. Patients with an LVEF greater than or equal to 0.40 represent a very large fraction of the post-MI population. The existence of an easy, low cost test that can be performed in a doctor’s office and determines which patients may benefit from defibrillator therapy represents a significant step forward in patient management. The publication reports that 74% of the patients studied had a negative MTWA test as might be expected in this population of post-MI patients who are at overall lower risk due to their preserved ejection fraction. Nine percent of the patients were indeterminate with some patient condition interfering with the measurement. However 17% of these patients were positive and therefore likely to benefit from therapy such as an implantable defibrillator.

“Recent studies have shown that an "abnormal" MTWA test (i.e. both positive and indeterminate results) is a useful marker for the identification of high-risk patients, and a negative or normal MTWA test is a marker of low risk. These studies assessed the value of MTWA in post-MI patients with a reduced LVEF” said Takanori Ikeda, MD, PhD, FACC, Professor of Medicine at Kyorin University and the study’s principal investigator. “In the present study, we assessed its value in patients with preserved cardiac function (i.e., a low-risk population). Interestingly, an indeterminate test result was not associated with arrhythmic events and "a positive MTWA test" alone had a significant association. We think that a positive MTWA test could be a strong risk stratifier for sudden cardiac death in the setting of acute MI and LVEF greater than or equal 0.40. At present, EP testing has been proposed to be a tool in identifying patients who would benefit from implantation of an ICD. However, EP testing is invasive, done in a hospital setting, and expensive. So, we would like to recommend noninvasive MTWA to detect high-risk patients, particularly in patients with preserved cardiac function.”

The study was a large collaborative cohort study enrolling 1,041 post-MI patients at eight medical centers in Japan. All patients had an LVEF greater than or equal 0.40 and the average LVEF was 0.55. Microvolt TWA testing was performed 48 to 66 days after acute MI, and 10 other risk variables were also evaluated.

The JACC article stated that “The end points were prospectively defined as sudden cardiac death or life-threatening arrhythmic events. During a follow-up of 32 +/- 14 months, 38 patients (3.7%) died of nonarrhythmic causes and were not considered for analysis. Of the 1,003 evaluable patients, 18 (1.8%) reached an end point. Microvolt TWA was positive in 169 patients (17%), negative in 747 (74%), and indeterminate in 87 (9%). A positive microvolt TWA test, nonsustained ventricular tachycardia, and ventricular late potentials were predictors of events, and percutaneous coronary intervention decreased the risk rate. On multivariate analysis, a positive microvolt TWA test was the most significant predictor, with a hazard ratio of 19.7 (p < 0.0001). This marker had the highest sensitivity and negative predictive value for events.”

“This is a significant study for Spectral Analytic Microvolt T-Wave Alternans™ as it points to the value of MTWA as a sudden cardiac death risk stratifier across the full spectrum of patients who have had an MI” said Jeffrey Langan, President and CEO of Cambridge Heart, Inc. “Our customer base routinely uses MTWA to determine if borderline and questionable patients with an LVEF ≤ 0.35 should receive an ICD or not. They also use it to demonstrate to those patients who are resistant to receiving an ICD that they do or do not need one. Now, as many of them have already begun to find out, it is useful in those patients with an LVEF greater than or equal 0 .40 in determining what therapeutic actions to take.”

About Cambridge Heart

Cambridge Heart (www.cambridgeheart.com) is engaged in the development and commercialization of products for the non-invasive diagnosis of cardiac disease, particularly the identification of those at risk of sudden cardiac arrest. The Company’s products incorporate its proprietary Microvolt T-Wave Alternans measurement technologies, coupled with its patented Spectral Analytic Method and ultra-sensitive disposable electrodes. Only Spectral Analytic Method MTWA tests are reimbursed by Medicare under its National Coverage Policy that covers patients with a wide variety of cardiac symptoms. Other major insurers in the USA also have coverage policies for the test. The T-Wave Alternans test is included in the Guideline for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death jointly developed by the American College of Cardiology (ACC), The American Heart Association (AHA) and the European Society of Cardiology (ESC). The Company, founded in 1990, is based in Bedford, Massachusetts and is traded on the OTCBB under the symbol CAMH.

About the Cambridge Heart Microvolt T-Wave Alternans Test

The Cambridge Heart Microvolt T-Wave Alternans Test measures extremely subtle beat-to-beat fluctuations in a person’s heartbeat called T-wave alternans. These tiny heartbeat variations – measured at one millionth of a volt – are detected in any clinical setting where titration of the heart rate is possible. The preparation for the test consists of placing proprietary sensors on a patient’s chest. Extensive clinical research has shown those patients with symptoms of, or who are at risk of, life threatening arrhythmias that test positive for T-wave alternans are at significant risk for subsequent sudden cardiac events including sudden death, while those who test negative are at minimal risk.

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