These days, people wear ribbons to support a multitude of diseases. Yet sudden cardiac death (SCD), a condition which claims more than 300,000 lives in the U.S. each year, has no symbolic presence. In fact, it receives less attention than heart attacks even though SCD makes up half of all heart disease-related deaths.
Why no big PR campaign or trail of therapies, diagnostics and lifestyle initiatives for this health problem?
"SCD is an event. The patient who dies from SCD generally doesn't exhibit much in the way of symptoms. It doesn't show up for its next meeting. That's it, it's over, rather than a progressive disease. That's why we don't see it as a clear and present danger," Ali Haghighi-Mood, PhD, CEO of Cambridge Heart (Tewksbury, Massachusetts), told Diagnostics & Imaging Week.
Cambridge Heart has a test for SCD and is working to change the current status quo for the condition. In the March issue of the journal Heart Rhythm, a special supplement includes five articles devoted to SCD – also known as sudden cardiac arrest – with a meta-analysis of 6,000 patients confirming the value of Cambridge's predictive test in evaluating a person's risk for SCD.
But that test, which has been on the market for at least four years, has been met with some resistance from the medical and reimbursement communities due to a lack of clear evidence. With this current battery of new studies, Haghighi-Mood said Cambridge Heart is trying to further prove the test's value.
Heart attacks typically occur as a result of a blockage in one ore more coronary arteries whereas SCD is the result of abnormal heart rhythms called arrhythmias. Death comes in just minutes and there are few warning signs or symptoms.
SCD can occur both in people who have been diagnosed with heart disease as well as those who have not. The Heartwave II System is designed to measure microvolt T-wave alternans (MTWA) to help predict a person's risk of SCD.
"It's a simple non-invasive test originally developed at Massachusetts Institute of Technology [Cambridge, Massachusetts] and is similar to a stress test," Haghighi-Mood said. "Fourteen electrodes are put on a patient who walks moderately on a treadmill. The whole test takes about 30 minutes. The heart rate needs to be elevated and the test analyzes for subtle variations in electrical activity. Study after study has shown that if the test is abnormal, the patient is at risk for SCD."
As part of that Heart Rhythm supplement, a meta-analysis and four other studies provide additional evidence that MTWA accurately predicts the risk of sudden cardiac arrest.
The meta-analysis was conducted by a group led by Stefan Hohnloser, MD, of the Division of Cardiology at JW Goethe University (Frankfurt, Germany), and assessed 13 MTWA clinical studies involving roughly 6,000 cardiac patients.
"The results demonstrate that MTWA testing is a consistently accurate predictor of sudden cardiac death and cardiac arrest in patients who do not already have implantable cardiac defibrillators [ICDs]," Hohnloser said. "These are the patients for whom MTWA testing is intended."
Other key conclusions from the studies found that:
Patients who test negative for MTWA abnormalities are at extremely low risk for SCD in the next year.
MTWA testing can help doctors guide ICD therapy to appropriate patients and overcome the widespread reluctance of patients and referring physicians to accept ICD therapy.
In clinical trials, appropriate ICD shocks are an unreliable surrogate endpoint for SCA and can skew results of risk stratification studies.
A meta-analysis of MTWA testing in patients with non-ischemic heart disease which analyzed eight trials involving 1,450 patients revealed that – in this population – negative MTWA results can help patients and their physicians decide whether ICD therapy may safely be avoided.
A review of several studies about the underlying cellular mechanisms of T-wave alternans concluded that MTWA is a marker of cellular changes that make the heart.
Cambridge Heart's technology is currently the only kind of MTWA test covered by Medicare and other insurers because it uses a method known as spectral analysis. But there's ongoing debate that this method isn't the best because it is subject to interfering noise.
Last year, GE Healthcare (Waukesha, Wisconsin) filed a petition with the Centers for Medicare & Medicaid Services to reimburse for their MTWA analysis employing the modified moving average (MMA) approach, and that petition was denied.
"Because the recently published meta-analysis dealt only with clinical studies that used the Spectral method, Cambridge Heart doesn't believe the meta-analysis will have any affect on CMS decisions regarding MMA," Haghighi-Mood said.
He said that the new data is unlikely to change the CMS' stance on MMA. That gives Cambridge Heart a key marketing advantage.
Moving forward, the company is actively participating in public awareness programs and is pursuing a strategy to establish partnerships to make the test more available to a larger number of physicians who are taking care of patients with elevated risk for SCD.
"That number is significant . . . north of 10 million in the U.S. alone," Haghighi-Mood said. "We can help identify those who are at high risk."