CORRELATION BETWEEN TIME-DOMAIN MEASURES OF HEART-RATE-VARIABILITY AND SCATTERPLOTS IN PATIENTS WITH HEALED MYOCARDIAL INFARCTS AND THE INFLUENCE OF METOPROLOL

Scatterplots (displays of each RR interval as a function of the preced ing RR interval) provide a visual assessment of nonrandom variations i n heart rate. In a recent study, scatterplot length, width, and area c orrelated with rime-domain measures of heart rate variability (HRV) in survivors of recent myocardial infarction (MI) receiving a beta block er. We performed this study to (1) assess the relation between rime-do main measures of HRV and scatterplot indexes in survivors of remote MI not receiving metoprolol and (2) to determine if metoprolol influence d scatterplot indexes. In 28 survivors of remote MI, HRV time-domain v ariables and scatterplot indexes were measured after 2 weeks off and 2 weeks on metoprolol. Off metoprolol, scatterplot length correlated wi th long-term HRV variables (SD of the difference of all RR intervals [ r = 0.98], SD of the average of all 5-minute intervals [r = 0.97]), an d scatterplot width correlated with shortterm HRV variables (root-mean -square successive differences between RR intrevals [rMSSD] [r = 0.88] ). Metoprolol increased time-domain HRV variables (mean RR interval, r MSSD, and proportion of adjacent RR intervals differing by >50 ms [pNN 50 (%)]) but did not alter scatterplot indexes, Thus, scatterplot inde xes correlate with time-domain measures of HRV in survivors of remote MI not receiving metoprolol. in contrast to HRV time-domain variables, scatterplot indexes are not influenced by metoprolol. (C) 1997 by Exc erpta Medico, Inc.