Study design: Retrospective cohort study.
Setting: Olmstead County Hospital, Rochester, Minn.
Synopsis: A chart review of AMI based on ICD-9 codes from 1987 to 2010 identified 3,010 patients. Patients were verified using symptoms, cardiac enzymes, and EKG changes at the time of event. Interventions evaluated included fibrinolytic therapy, CABG, or primary PCI.
Survival increased to 96% from 89% during the period from 1987 to 2010. Researchers also noted more comorbid conditions, such as diabetes mellitus, COPD, and hypertension, noted over time. Of the patients evaluated, 643 readmissions occurred for 561 patients (18.6%). Of these, the most frequent causes were ischemic heart disease, respiratory symptoms, and heart failure. Comorbid conditions, such as diabetes, COPD, anemia, higher killip class on initial admission, duration of prior hospitalization, and procedural complications, independently increased the risk of readmission.
Bottom line: In addition to factors unrelated to an AMI, a patient’s comorbid conditions, post-procedure complications, and duration of hospitalization influence the risk of readmission.
Citation: Dunlay SM, Weston SA, Killian JM, et al. Thirty-day rehospitalizations after acute myocardial infarction: a cohort study. Ann Intern Med. 2012;157(1):11-18.
One-Hour Rule-Out or Rule-In for AMI in Chest Pain
Clinical question: How can we use the newly developed high-sensitivity cardiac troponin (hs-cTnT) to shorten the time to rule in and rule out AMI?
Background: The hs-cTnT assays available appear to improve the early diagnosis of AMI when compared to the regular cardiac troponins, but no clear guidelines are available as how to best use them in clinical practice.
Study design: Prospective, multicenter study.
Setting: Switzerland hospitals.
Synopsis: The study enrolled 872 unselected patients presenting to the ED with acute chest pain. Hs-cTnT level was measured in a blinded fashion at presentation and after one hour. Two independent cardiologists using all available medical records adjudicated the final AMI diagnosis. Optimal thresholds for rule-out were selected to allow for 100% sensitivity and negative predictive value. Rule-out criteria were defined as baseline hs-cTnT level <12 ng/L and an absolute change within the first hour of <3 ng/L. Rule-in criteria was defined as baseline hs-cTnT >52 ng/L or an absolute increase within the first hour of >5 ng/L.
AMI was the final diagnosis in 17% of patients; AMI was ruled out in 60%; and the remaining 23% were placed in observation.
Primary prognostic endpoint was 30-day mortality rate, which was 0.2% in the rule-out group, validating the suitability of these patients for early discharge.
Study limitations were that it was an observational study not used for clinical decision-making, no dialysis patients were included, and only one specific hs-cTnT assay was tested.
Bottom line: Using hs-cTnT levels at presentation and absolute changes within the first hour, a safe rule-out or rule-in of AMI can be performed in 77% of patients presenting with chest pain.
Citation: Reichlin T, Schindler C, Drexler B, et al. One-hour rule-out and rule-in of acute myocardial infarction using high-sensitivity cardiac troponin T. Arch Intern Med. 2012;172(16):1-8.
Aspirin Increases Bleed Risk without Reducing Risk of Stroke in CKD and NVAF Patients
Clinical question: Is there a difference between aspirin and warfarin in preventing thromboembolic complications and risk of bleeding in patients with chronic kidney disease (CKD) and nonvalvular afib (NVAF)?
Background: Data are lacking on risks and benefits of aspirin and warfarin in CKD, as this group of patients largely has been excluded from anticoagulation therapy trials for NVAF. This study examined the risks and benefits of aspirin and warfarin in patients with CKD with NVAF.
Study design: Retrospective, observational cohort study.
Setting: Danish National Registries.