Sequence versus phenylephrine assessment of the baroreflex gain in post-myocardial infarction patients

The authors compared the baroreflex gain (BRG) measured by the phenylephrine technique (Phe-BRG) with BRG measured by the sequence technique (Seq-BRG) in 50 post-myocardial infarction patients (age: 52/spl plusmn/8 years, LVEF: 42/spl plusmn/12%). Correlation analysis was performed to assess the degree of linear relationship between Phe-BRG and Seq-BRG. The agreement was investigated computing the bias and the limits of agreement of the 2 measures and of the percentage difference between the 2 measures. The authors found a moderate degree of linear association (correlation coefficient=0.67). The bias was 2.2 ms/mmHg (p<0.05), indicating that on average, the sequence method gives a higher value for BRG than the phenylephrine test. The agreement was poor, as the limits of agreement were. -7.3+11.7 ms/mmHg. The corresponding percentage values were: 27% for the bias and -67+122% for the limits of agreement. These results indicate that using one method or the other can lead to significantly different results and that the 2 methods can be used as alternatives only for screening purposes.