Chronotropic response during exercise testing in old people

The possibility of a depressed chronotropic response to exercise in old people as an early signs of sinus node disfunction, was studied in 118 subjects over 60 years (group A) and 25 subjects under 60 years (group B), subjected to a maximal, symptom limited, exercise test (ET) using a cycloergometer. There were no significant statistical differences between the two groups as regards the heart rate (HR) at rest, increase of HR at each effort level, and mean chronotropic impairment (Chl). The mean values were the same when the subjects over 65 years were considered separately (group C). But, when the chronotropic response to ET was studied individually, it was depressed (HR increment less than 15 beats/min at each level) in 22.3% of subjects in group A and only in 4% in group B. The depression was important (increment less than 10/min) in 15% of the subjects in group A and in none of those in group B. The results suggested that about 1/4 of the old people have depressed chronotropic response to exercise attributed by us to a subclinical sinus node disfunction.