Association of ACS with Mortality and Morbidity

Cincinnati—Acute coronary syndrome (ACS) is one of the most commonly diagnosed cardiovascular illnesses in the United States and one that is responsible for significant morbidity and mortality. Nearly 1.2 million hospital discharges were associated with a diagnosis of ACS. The diagnosis includes unstable angina (UA) and myocardial infarction (MI) with or without ST-segment elevation.

For Medicare beneficiaries between 2006 and 2009, the median risk-standardized 3-day readmission rate after acute MI was 19.9%; up to 30% of discharged patients were readmitted after 6 months during that same time period. Among Medicare beneficiaries (average age, late 70s) with acute MI, the 30-day mortality rate was 16% following related hospital admission.

Researchers recently conducted a study to document the rate at which patients develop additional cardiovascular comorbidites and mortality over a 3-year period following the initial ACS event. They reported study results during a poster session at the AMCP meeting. The poster was titled Acute Coronary Syndrome (ACS): Mortality and Morbidity following a Diagnosis of ACS.

The study measures were demographics and clinical characteristics, including age, sex, and race, and time to atrial fibrillation (AF), heart failure (HF), or death. The researchers utilized the 5% Medicare database, a random sample of all Medicare patients followed over multiple years. Eligible patients were ≥65 years of age with a hospitalization claim containing a code for acute MI or UA during 2005-2006; inclusion criteria included no evidence of prior ACS, AF, or HF in the year before ACS, and had survived hospitalization.

The end point was a composite of AF, HF, or death.

Following application of exclusion and inclusion criteria, the study included 19,427 Medicare patients with a new diagnosis of AF and no evidence of prior AF or HF. Of those, 45% were 75 to 84 years of age and 53% were male.

Within 3 years, 35% of the patients in the study developed AF, HF, or both; 5% developed AF alone, 23% developed HF alone, and 7% developed both AF and HF. Of the patients with newly diagnosed ACS, 29% were expected to develop AF or HF or die within 1 year; 45% within 3 years. Nine percent of patients were expected to die within the first year; 18% within 3 years.

The risk of AF, HF, or death increased 3% with every 1-year increase in age (P<.001). Black patients had a 10% higher risk of AF, HF, or death compared with white patients (P=.16).

The analysis also found that among patients with comorbidites of chronic kidney disease and diabetes, the risk of death, AF, or HF within 3 years following ACS was increased by 57% and 26%, respectively (P<.001 for both comparisons). Patients with chronic obstructive pulmonary disease, liver disease, or venous thrombophlebitic disease had a roughly 40% higher risk of death, AF, or HF compared with patients without each disease (P<.0001 for all comparisons).

The researchers cited 2 limitations to the study: (1) identification of the patients’ diagnoses was based solely on claims reimbursed by Medicare and (2) the retrospective observational design of the study allowed potential selection bias; the only information available was from a claims database. The effect of unmeasured variables, such as physician treatment selection, is unknown.

In conclusion, the researchers noted that in the study population of Medicare beneficiaries ≥65 years of age, the risk of developing AF, HF, or death increased with age, and black patients were at a higher risk than white patients. “ACS is a red flag for the development of additional cardiovascular disease and mortality, especially in patients with chronic illnesses such as diabetes and kidney disease,” they added.

This study was supported by Janssen Scientific Affairs, LLC.