Arrhythmias on ambulatory electrocardiographic monitoring in women without apparent heart disease.

Cardiac arrhythmias were evaluated in apparently normal women by randomly selecting within the age decades of 20 to 60, 200 of the 788 women employees of a company. After exclusions for cardiac and medical reasons and refusals to participate, 101 subjects underwent 24-hour ambulatory electrocardiographic monitoring. The mean heart rate was 82 beats/min, but was higher in smokers (p less than 0.05). Premature supraventricular contractions were present in 28 of 101 subjects (28%); the prevalence increased with age (p less than 0.001), but the frequency was less than 1 per hour in 24 of 28. PVCs occurred in 34 of 101 subjects (34%); the frequency was less than 1 per hour in 25 of 34. The PVCs were complex (Lown grade 3 or higher) in 10 (10%) and multifocal in 9 of 10; there was 1 couplet each in 3 and 1 run of 4 PVCs in 1 subject. PVCs were present in 20 of 42 subjects (48%) taking any medication (primarily oral contraceptives, estrogenic hormones and maintenance thyroid), compared with 14 of 59 subjects (24%) not taking medication (p less than 0.01). In women younger than 40 years, PVCs were present in 8 of 15 women (53%) taking contraceptives, compared with 4 of 33 (12%) not taking contraceptives (p less than 0.001). PVCs occurred in 7 of 12 subjects (58%) taking thyroid medication, compared with 27 of 89 (30%) not taking thyroid medication (p less than 0.03). In the 59 subjects not taking medication only 1 subject averaged more than 1 PVC/hour and 1 had 1 couplet.(ABSTRACT TRUNCATED AT 250 WORDS)