Medicare has ruled that microvolt T-wave alternans testing should be covered nationally, calling it an accurate screen for sudden cardiac death.
The test is used primarily to determine candidates for an implantable cardioverter defibrillator, but the Centers for Medicare and Medicaid Services did not require use of the diagnostic to select those patients.
“CMS has determined that MTWA is a useful risk stratification tool and can identify which heart patients are at negligible risk of sudden death, and who may therefore be able to avoid ICD implantation and its attendant risks,” the agency wrote in its coverage decision.
The test is manufactured and sold by Cambridge Heart Inc., based in Bedford, Mass. It was originally approved by the Food and Drug Administration in 2000, but has not been widely adopted. According to the company, only 500 of the $30,000 units have been sold.
Dr. Anne B. Curtis, president of the Heart Rhythm Society, said that clinicians have not been quick to adopt MTWA testing. Although it has been shown to have a high negative predictive value, it has not given clinicians confidence that patients with normal results have a very low likelihood of having a cardiac event, Dr. Curtis said in an interview.
ICDs have been shown to improve survival in patients with an ejection fraction at or below 35%, so there is no real incentive to conduct MTWA testing in those patients, especially since so many still have not received ICDs, said Dr. Curtis, who is also chief of cardiovascular services at the University of South Florida, Tampa.
In those high-risk patients, “you clearly would want that patient to have a defibrillator—you don't need any other tests,” agreed Dr. Michael J. Mirro, a trustee of the American College of Cardiology and medical director of the Parkview Research Center, Fort Wayne, Ind. “Where it is going to be of value—and why the academic electrophysiologists are waiting for more clinical data—is to see if it has more compelling positive predictive value in patients in the intermediate-risk group,” Dr. Mirro said in an interview. Dr. Mirro is a shareholder in Cambridge Heart.
Both Dr. Mirro and Dr. Curtis agreed that positive data from an ongoing prospective study, the Alternans Before Cardioverter Defibrillator (ABCD) trial—in addition to wider insurance coverage—would prompt more widespread use of MTWA testing.
The diagnostic has been evaluated prospectively in patients with ischemic cardiomyopathy, nonischemic dilated cardiomyopathy, or mixed cardiomyopathy. In the 19 prospective studies reviewed by CMS, patients had an ejection fraction of 23%–71%. Patients with indeterminate test results were excluded. Overall, the positive predictive value ranged from 0% to 67%, and the negative predictive value ranged from 71% to 100%.
The Heart Rhythm Society and ACC wrote to CMS to urge against making MTWA testing a prerequisite for ICD implantation. Several manufacturers took the same position, and said that Medicare should wait for the results of the ABCD study.
That 42-center trial is being led jointly by St. Jude Medical Inc., Case Western Reserve's MetroHealth Medical Center, and Cambridge Heart. Patients with a positive MTWA test are given an ICD and then followed for a year to evaluate ventricular tachyarrhythmia and death rates. Enrolled patients have ischemic heart disease, a left ventricular ejection fraction less than or equal to 40%, and nonsustained tachycardia.
MTWA testing was previously covered by CMS local contractors and, according to David Chazanovitz, CEO of Cambridge Heart, 10 BlueCross BlueShield plans—even though an October 2005 review by the BlueCross BlueShield Association's Technology Evaluation Center said there was insufficient evidence to recommend the testing. Aetna recently agreed to cover MTWA on a national basis, said Mr. Chazanovitz in an interview.
Currently, about 1.3 million Americans have been deemed eligible for an ICD.