NEW YORK (Reuters Health) - A relatively small proportion of Medicare beneficiaries receive rehabilitation therapy following a heart attack or bypass surgery, although the usage rates vary widely among states.

The report was published in the medical journal Circulation.

Lead author Dr. Jose A. Suaya and colleagues at Brandeis University, Waltham, Massachusetts, examined Medicare records for 267,427 patients age 65 or older who had a heart attack or had undergone bypass surgery in 1997.

Of the study group, just 19 percent participated in at least one session of outpatient cardiac rehab after hospital discharge. For heart attack patients, the rate was 14 percent and for bypass surgery patients, 31 percent.

Those who did participate attended an average of 24 sessions, although women, older patients, non-whites and patients also receiving Medicaid had fewer sessions on average.

The most striking differences in cardiac rehab use were by state, ranging from a low of 6.6 percent in Idaho to a high of 53.5 percent in Nebraska. In general, use was highest in the north central states and lowest in the South.

Further analysis showed that patients living in zip codes with the highest levels of median household income and education were 23 and 33 percent more likely, respectively, to use cardiac rehab than those living in zip codes with the lowest levels of income and education.

Although not examined in the study, several factors are potentially important if the use of cardiac rehab is to be increased in these patients, the investigators told Reuters Health.

Five key factors include:

1. Doctor's referral to cardiac rehab.
2. Patient's awareness of cardiac rehab's benefits.
3. Availability of cardiac rehab services near the patient's residence.
4. Appropriate reimbursement rates that allow cardiac rehab facilities to cover their operational costs.
5. Patient's ability to get to cardiac rehab, for example, by public transportation, his or her own vehicle, or a ride with a family member