Minimal heart rates and longest pauses in healthy adult subjects on two occasions eight years apart.

A 24-h Holter monitoring (HM) record was obtained on two occasions 8 years apart in 183 healthy subjects (120 male and 63 female), aged 40-85 years. The purpose of the study was to determine the minimal mean heart rate (HR-min) and longest pauses in heart rhythm, and to examine possible changes in these parameters over a longer period of time. (HR-min was calculated from a 1-min sample period.) HR-min was influenced by physical activity level and smoking habit, but was independent of age. Females had higher HR-min than males. In the male group mean HR-min was 54 beats min-1 and 53 beats min-1 on the two recordings (P greater than 0.05) (range 36-75 beats min-1 and 38-69 beats min-1). HR-min less than 40 beats min-1 was seen in 2.5% of the males. In the female group, the lowest recorded HR was 42 beats min-1 and mean HR-min on the two recordings was 58 beats min-1 and 56 beats min-1 (P less than 0.001). The paired HR-min observations were highly correlated. In all subjects, pauses greater than or equal to 1.75 s were registered in 6% and 6.5% on the two recordings. The occurrence of pauses was related to low HR-min. Above the age of 60 years sinus arrest was the type of pause most often seen.(ABSTRACT TRUNCATED AT 250 WORDS)