Israel Medical Association Journal

Background: Microvolt T-wave alternans (MTWA) measures subtle beat-to-beat fluctuations in the T-wave amplitude. It was found to be associated with cardiac electrical instability in patients with ischemic and dilated cardiomyopathy.

Objectives: To investigate the reproducibility of the MTWA test results in patients with ischemic heart disease.

Methods: The study group comprised patients with ischemic heart disease who participated in a rehabilitation program at the Assaf Harofeh Medical Center. MTWA was measured during a bicycle exercise test at the first encounter and repeated after one week.

Results: Of the 40 study patients with coronary artery disease, 4 had an indeterminate result and were excluded from the data analysis; 5 had a positive MTWA in the first and second study (14%), 27 had a negative MTWA in the first and second study (75%), and 4 had a negative MTWA in the first study and a positive MTWA in the second study (11%). Overall, there was a correlation between the results of the first and the second study in 89% of the patients (kappa = 0.652, P = 0.0001).

Conclusions: MTWA measurements are reproducible in the short term in patients with coronary artery disease.

Background: Elevated fibrinogen, considered an independent risk factor for coronary disease, stratifies an individual as high risk for coronary disease. A risk marker requires little intra-individual variability during a long period.

Objectives: To establish intra-individual variability of fibrinogen levels in patients with coronary disease.

Methods: We investigated fibrinogen levels prospectively in four blood samples drawn from 267 patients with a history of arterial disease (arterial group) and from 264 patients with cardiac valve replacements (valvular group). The samples were taken during the course of 78.7 and 78.8 days from the arterial and valvular groups respectively.

Results: Marked intra-individual dispersion with a reliability coefficient of 0.541 was found in the arterial group and 0.547 in the valvular group. The Bland-Altman test showed low probability to obtain similar results in different samples from the same individual. These results show large intra-individual variability, with similarities in the arterial as well as in the valvular group.

Conclusions: It is not possible to stratify a patient by a specific fibrinogen dosage.