Effects of sex and age on electrocardiographic and cardiac electrophysiological properties in adults

Although differences in patient sex in heart rate and QT interval have been well characterized, sexual differences in other cardiac electrophysiological properties have not been well defined. The study population consisted of 354 consecutive patients without structural heart disease or pre-excitation who underwent clinically indicated electrophysiological testing in the drug-free state. Atrial, AV nodal, and ventricular effective refractory periods (AERP, AVNERP, VERP) were determined at a pacing cycle length of 500 ms using an 8-beat drive train and 3-second intertrain pause. There were 124 men and 230 women with a mean age of 45 ± 19 and 47 ± 18 years, respectively. The sinus cycle length (SCL) was longer in men than in women (864 ± 186 and 824 ± 172 ms, respectively, P < 0.05). The QRS duration was significantly longer in men (90 ± 12 ms) than women (86 ± 13 ms) (P < 0.005). The HV interval was 48 ± 9 ms in men and 45 ± 8 ms in women (P < 0.05). The sinus node recovery time (SNRT) was significantly longer in men than in women (1215 ± 297 ms and 1135 ± 214 ms, respectively, P < 0.05). AERP and VERP were similar in both sexes. Aging did not influence sexual differences in cardiac electrophysiological properties, although, it independently prolonged the SCL, PR, and QT intervals, AH and HV intervals, SNRT, AVNERP, and the AV Wenckebach cycle length. The SCL, QRS duration, HV interval, and SNRT were significantly longer in men than in women. Aging prolonged cardiac conduction and increased the SCL but the effects were similar in both sexes. AERP and VERP were unaffected by aging or sex.