The cost per year of quality life for giving ICDs only to risk-stratified patients who had been tested with MTWA was about $50,000, compared with medical therapy. 'This is well within the usual range considered cost-effective for new medical technologies,' said the study's lead author.

The test actually could save Medicare hundreds of millions of dollars in the long run, suggests a study led by University of Michigan researchers.

The team used a sophisticated computer model to calculate the potential impact of using the test MTWA to help determine which patients would benefit most from implanted devices that automatically re-start a stopped heart.

Those devices, called implantable cardioverter defibrillators, or ICDs, have been shown to save lives that would otherwise have been lost to sudden cardiac death, which kills 300,000 Americans each year.

Risk Stratification

Medicare expanded its coverage of ICDs a year ago, and an estimated 500,000 people over age 65 are now candidates to receive this device. ICDs cost $35,000 including implantation. They require periodic battery replacement and pose a device failure risk. Covering the cost of ICDs for patients who have the same characteristics as participants in the trial that led to Medicare approval could add $3 billion annually to the program's budget.

A significant fraction of those costs could be spared if doctors focused on providing ICDs only to patients with an abnormal or inconclusive MTWA test result, the researchers suggest in a presentation at the American College of Cardiology (ACC) Scientific Session. Previous studies have suggested that patients with a negative, or normal, MTWA test result have a far lower risk of sudden cardiac death than others.

Risk stratification could potentially save Medicare $690 million a year -- even after the costs of the MTWA test and the care of patients who don’t receive ICDs are taken into account, the researchers estimate.

"ICDs have been shown in several studies to be cost-effective, which means the cost is considered acceptable given the benefit to patients," says lead author and University of Michigan cardiology fellow Paul Chan, MD, MSc. "But a very expensive device can be cost-effective and still not affordable to society if the condition it treats is highly prevalent. Our study demonstrates the potential impact of using additional factors to aid decisions about the use of expensive devices."

The MTWA test, he notes, is gaining acceptance among cardiologists but will likely become more common if Medicare decides to cover it.

Best Case/Worst Case Scenarios

Microvolt T-wave alternans are small variations in the electrical impulses in the heart. They can't be detected on the conventional heart-rhythm test called the electrocardiogram (ECG), but MTWA test equipment can detect them via special sensors placed on the patient's body during a brief exercise session.

For the study being presented at the ACC meeting, which has been accepted for publication in JACC, Chan and his colleagues used a computer model called a Markov analysis to simulate the costs, benefits and health outcomes of 65-year-old individuals who meet the MADIT-2 trial criteria for Medicare coverage of an ICD. They looked at three scenarios: All such patients get an ICD; only those with positive or inconclusive MTWA results receive an ICD; or no patients get an ICD.

The model used a range of assumptions about what percentage of patients would suffer sudden cardiac problems and long-term complications with or without an ICD, and how many ICD patients would suffer complications related to their ICDs. It also included assumptions about what proportion of patients would die depending on their treatment or MTWA status.

All of these assumptions were based on data from previous ICD trials, or best case/worst case scenarios. Costs for care were also included, such as MTWA test costs, ICD costs, and the cost of medical care for those who stayed healthy or suffered a heart problem with or without an ICD.

Cost per Year of Quality Life Saved

To account for the uncertainties inherent in each of the clinical variables, the researchers performed various levels of sensitivity analyses, including one using 10,000 simulations in which all model variables were randomly sampled. Known as a Monte Carlo simulation, this analysis allowed them to examine the distribution of possible cost-effectiveness ratios for every quality-adjusted life year (QALY) saved, and is a standard way to assess the cost-effectiveness of a medical intervention.

It allows researchers to assess the cost of saving a year of a person's life, adjusted for the quality of that life and the life-saving power of a particular course of action.

In general, the cost per QALY for giving ICDs only to risk-stratified patients who had been tested with MTWA was about $50,000, compared with medical therapy.

"This is well within the usual range considered cost-effective for new medical technologies," says Chan.

However, compared with MTWA testing followed by ICD use only in those with a positive or inconclusive MTWA result, the all-ICD option would cost $88,700 per QALY gained -- under best-case scenarios.

Chan cautions that the new results are not meant to guide doctors in decisions about whether or not to suggest that particular primary prevention patients receive ICDs.

However, he hopes the data may be useful in decisions about how to spend resources for this type of care. Additionally, he hopes that further research will examine how often doctors should conduct MTWA tests in patients who don't receive an ICD to help them monitor for changes in sudden cardiac death risk over time that might warrant one.