HarrisCom Blog

This week at the annual Scientific Sessions of the American Heart Association (AHA) ,  the renowned Framingham Heart Study released the alarming findings that one in eight males and one in 24 females in the US who reach the age of 40 are likely to die of sudden cardiac arrest (SCA).

 According to the AHA, 12 M Americans are at risk of SCA–and every  year, some 350  thousand US  individuals die of SCA, making SCA one of this nation’s leading killers.

But—there is hope. Also at the AHA, a Japanese research team released clinical trial results reaffirming that a non-invasive treadmill test developed by Cambridge Heart, Inc.,  of Tewksbury MA, can effectively predict the risk of sudden cardiac arrest for many cardiac patients—and can quite accurately which patients are NOT at risk.  (Disclosure; I’m paid to help Cambridge Heart with media relations).

The test, called MTWA (Microvolt T-wave Alternans)  measures a tiny heartbeat irregularity believed to cause SCA. Administered on a treadmill like a stress test, the MTWA test helps doctors assess whether riskier, more costly invasive testing is needed.  While studies show that MTWA is often as accurate as invasive testing in predicting SCA, invasive (and potentially risky) electrophysiology  tests are still generally used to determine whether cardiac defribrillators—which shock stopped hearts back into action-  should be implanted.

 The newly reported study, which enrolled 458 patients in 38 medical centers in Japan, was called “ PREVENT-SCD” (PRospective EValuation of VENtricular Tachyarrhythmic Events and Sudden Cardiac Death in Patients with Left Ventricular Dysfunction  It included patients with cardiomyopathy and ejection fraction of 40% or lower. In the study, 280 patients underwent non-invasive MTWA testing using the analytic spectral method and were followed for up to three years.

At a median follow-up time of 36 months, patients with an abnormal MTWA test were 4.4 times more likely to experience a life-threatening arrhythmia or SCD than those with a normal test, the researchers found. The 3-year negative predictive value was reported to be 97.0%, indicating that patients with a normal or negative MTWA test are at low risk for experiencing sudden death.

According to lead author Satoshi Shizuta, MD, of Kyoto University Hospital, Kyoto, Japan, “MTWA has a very high negative predictive value for lethal arrhythmias in this population He noted that these patients are at very low risk for SCD in the next three years.

According to Dr. Ali Haghighi-Mood, President and Chief Executive Officer of Cambridge Heart, “The PREVENT-SCD trial further confirms the results of several previously published studies of MTWA in patients with left ventricular dysfunction…The value of MTWA as an accurate predictor of sudden cardiac arrest in this population has become very well established.”

The  Japanese trial was not funded by Cambridge Heart, nor was Cambridge Heart aware of the results before they were announced at AHA. 

However, the Japanese announcement follows close on the heels of a joint announcement last week by Cambridge Heart and Cardiac Science, a Washington State stress test manufacturer, that the two companies will collaborate on developing a “super stress test” that will include an MTWA testing component.

More information about the Japanese trial is available on Cambridge Heart’s Web site at <http://cts.businesswire.com/ct/CT?id=smartlink&url=http%3A%2F%2Fwww.cambridgeheart.com%2Fcontent%2FShared%2FFAQ.shtml&esheet=6103292&lan=en_US&anchor=MTWA&index=1&md5=a98add7e8a88beb9b2b0e62edffa32f7> ) . The Web site (www.cambridgeheart.com) also offers information about SCA, other studies of MTWA, and the MTWA test itself.  The test is reimbursable by Medicare and many private insurers.

—Anita M. Harris

HarrisComBlog is a publication of the Harris Communications Group of Cambridge MA. We also publish the New Cambridge Observer.