Rates of post-discharge mortality for patients with acute MI (AMI) have increased, and researchers said this is due to higher non-cardiovascular mortality in older patient populations, according to a study published in the November issue of Circulation: Cardiovascular Quality and Outcomes.

To better evaluate mortality trends among AMI patients admitted to N.J. hospitals, William J. Kostis, MD, PhD, of the University of Medicine and Dentistry in New Brunswick, N.J., used the MIDAS (MI Data Acquisition System) to examine 285,387 patients hospitalized for a first AMI between Jan. 1, 1986, and Dec. 31, 2008, to assess comorbidities, complications, interventions and length of stay.

Kostis and colleagues found that mortality at hospital discharge decreased from 16.9 percent to 7.5 percent. However, the decrease in the death rate at one-year post-discharge was less pronounced, at 6.4 percent, which the authors attributed to the increase in the rates of mortality at one-year post-discharge from 12.1 percent to 13.9 percent.

Mortality from a hospital admission to 30 days decreased from 18.2 percent to 10.2 percent, an 8 percent decrease, while mortality rates from admission to one-year decreased from 26.6 percent to 20.2 percent. The researchers  reported that 30-day post-discharge mortality increased among patients discharged alive by 0.6 percent, from 3.3 percent to 3.9 percent.

Compared to 1986, the rates of mortality from 30 days to one-year after discharge increased in 2007, from 8.7 percent to 10 percent.

Non-cardiovascular disease (NCVD) post-discharge mortality was more pronounced in the older patient population compared with the youngest age groups, but post-discharge NCVD mortality at 30 days doubled within the youngest patient population, from 0.18 percent to 0.36 percent. For the oldest age group, this increased eight-fold, from 0.39 percent to 3.32 percent.

Post-discharge NCVD mortality at one-year increased from 0.84 percent to 1.64 percent and increased four-fold from 3.61 percent to 16.23 percent in the oldest age group. The most frequent causes of NCVD death were diabetes, respiratory and renal disease and cancer.

"The decrease in CVD mortality combined with older age and higher rates of comorbidities has resulted in higher NCVD mortality after discharge. We can speculate that the shorter length of stay in recent years may have contributed to the increase in post-discharge mortality at 30 days by displacing some deaths from the inpatient to the outpatient setting," the authors wrote.

"A small portion of the increase may be due to shortening of the length of stay, with displacement of some deaths from the inpatient to the outpatient setting. However, this cannot explain the increase in mortality occurring between 30 days and one year after discharge.

"Attention to comorbidities during hospitalization or soon after discharge and preventive and/or therapeutic strategies for diabetes, cancer, and respiratory and renal disease should become a routine part of post-AMI patient care and may result in better long-term outcomes."

The authors stated that controlled trials or registries would be beneficial to evaluate whether diagnostic, preventive or therapeutic interventions could improve long-term outcomes of AMI patients.