Evaluating cardiac vagal activity on a conventional electrocardiogram.

Objective: To determine the viability of using a conventional electrocardiogram (ECG) tracing for assessment of CVA.

Methods: We retrospectively analyzed 1395 individuals (995 males), aged 46 +/- 17.2 years (mean +/- standard deviation) with conventional ECG tracings to measure the delta RR (which represents the difference in milliseconds (ms) between the greatest and smallest RR interval) and results of a second autonomic parasympathetic evaluation, the 4-second exercise test (T4s), that quantifies CVA by the cardiac vagal index (CVI).