Majority of rehospitalizations after MI are for unrelated causes

More than 40% of 30-day rehospitalizations after a myocardial infarction (MI) were related to the MI, while the rest were due to other causes or for unclear reasons, reported a study.

Also, comorbid conditions, longer length of stay, and complications of angiography and revascularization or reperfusion were associated with increased 30-day rehospitalization risk, according to results published in the July 3 Annals of Internal Medicine. The retrospective cohort study used a population-based registry in Olmsted County, Minn., of 3,010 patients who were hospitalized with first-ever MI from 1987 to 2010.

A total of 643 rehospitalizations occurred among 561 (18.6%) patients within 30 days of discharge. The most common reasons were ischemic heart disease, respiratory or chest symptoms, and heart failure. Overall, 42.6% of the rehospitalizations were related to the first MI or its treatment, whereas 30.2% were unrelated and 27.2% had an unclear relationship (most often cited as atypical chest pain). Unrelated rehospitalizations were more common in women and patients with non-ST-elevated MI.

Among the conditions independently associated with increased risk for rehospitalization after MI were:

• diabetes mellitus (hazard ratio [HR], 1.34; 95% CI, 1.10 to 1.63),
• chronic obstructive pulmonary disease (HR, 1.43; 95% CI, 1.15 to 1.79),
• anemia (HR, 1.25; 95% CI, 1.03 to 1.50),
• Killip class 2 to 4 at presentation (HR, 1.22; 95% CI, 1.01 to 1.46),
• four- to seven-day length of stay during index MI hospitalization (HR, 1.34; 95% CI, 1.05 to 1.70),
• more than seven-day length of stay during index hospitalization (HR, 1.65; 95% CI, 1.27 to 2.14),
• complication of angiography during index hospitalization (HR, 2.40; 95% CI, 1.43 to 4.01) and
• complication of reperfusion or revascularization during index hospitalization (HR, 2.12; 95% CI, 1.61 to 2.80).

“[P]atients affected by a vascular or bleeding complication, stroke, or acute kidney injury after angiography or revascularization or reperfusion represent a high-risk population for rehospitalization,” the authors concluded. “Prevention of complications and close follow-up for patients who have had a complication may be of particular importance for preventing rehospitalizations.…[P]atients with MI have many comorbid conditions, which may affect rehospitalization. The management of patients with multiple comorbid conditions and competing risks is of increasing importance as the population ages.”