Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse drug reaction caused by heparin. As thrombocytopenia is common in hospitalized patients receiving heparin, it would be useful to have a clinical scoring system that could differentiate patients with HIT from those with other reasons for thrombocytopenia. AIM: To compare prospectively the diagnostic utility of a clinical score for HIT in two different clinical settings. METHODS: The pretest clinical scoring system, the '4 T's', was used to classify 100 consecutive patients referred for possible HIT in one hospital (Hamilton General Hospital, HGH) into high, intermediate, and low probability groups. This system was also used to classify likewise 236 patients by clinicians in Germany referring blood for diagnostic testing for HIT in Greifswald (GW). The clinical scores were correlated with the results of laboratory testing for HIT antibodies using the serologic criteria for HIT with high diagnostic specificity. RESULTS: In both centers, patients with low scores were unlikely to test positive for HIT antibodies [HGH: 1/64 (1.6%), GW: 0/55 (0%)]. Patients with intermediate [HGH: 8/28 (28.6%), GW: 11/139 (7.9%)] or high scores [HGH: 8/8 (100%), GW: 9/42 (21.4%)] were more likely to test positive for clinically significant HIT antibodies. The positive predictive value of an intermediate or high clinical score for clinically significant HIT antibodies was higher at one center (HGH). CONCLUSIONS: A low pretest clinical score for HIT seems to be suitable for ruling out HIT in most situations (high-negative predictive value). The implications of an intermediate or high score vary in different clinical settings.

Biphasic cardioversion of acute atrial fibrillation in the emergency department.

INTRODUCTION: There is a trend towards accelerated management of acute atrial fibrillation (AF) in the emergency department (ED). We report our experience with biphasic cardioversion of acute AF. METHODS: This was a prospective, descriptive study at a tertiary hospital ED over a 6 month period. Acute AF was defined as symptoms that had been present for <48 hours. Patients who received biphasic cardioversion for acute AF in the ED were enrolled. Data collected included: patient demographics, past medical history, details of biphasic cardioversion, outcome, complications, disposition, and length of stay. RESULTS: There were 34 attempts at cardioversion in 33 patients. The mean (SD) age was 56 (16) years and 21 patients (64%) were men. Biphasic cardioversion was successful in 31 attempts (91%). In 24 attempts (71%), 100 J was selected as the initial energy level. This was successful in 21 attempts (88%). There were three minor complications related to sedation. The mean (SD) length of stay was 5.6 (2.8) hours in the ED and 15 (25) hours in the hospital. The three patients who failed to revert were older (mean age 64 years), had underlying cardiovascular disease, and spent longer in hospital (50 v 12 hours, p = 0.01). Telephone follow up was conducted with 32 patients (97%) at 3 months. Recurrence of AF occurred in 7 patients (22%). Most patients (31, 97%) were satisfied with the biphasic cardioversion. CONCLUSIONS: Biphasic cardioversion of acute AF is effective. The majority of patients can be managed as outpatients, and there is very high patient satisfaction with this approach. An initial shock energy level of 100 J is usually effective.