Background: This research study aimed at assessing the electrocardiographic (ECG) changes caused by ageing in a cohort of healthy subjects with normal echocardiographic examinations. Methods: A total of 219 healthy individuals (119 males and 100 females) were evaluated for possible arrhythmias with a standard 12-lead resting ECG and 24-h Holter ECG. As the recordings were performed between 1998 and 2000, a 20-year follow-up study was carried out by assessing the local medical records to investigate whether the subjects had experienced any cardiovascular health complications or disease since the baseline assessment. Results: Eighty-three subjects (45 males and 38 females) presented with pathological ECG findings at baseline. The most common finding on analysis of Holter ECG recordings was premature atrial contractions, and the most severe pathological finding was episodes of ventricular tachycardia (eight subjects). Regarding the analysis of the standard 12-lead ECG, the most common finding was left ventricular hypertrophy, and the most severe pathological findings were ST-T changes and prolongation of the QT interval. Despite other cardiac examinations performed on these patients showing normal results, in combination with a strict inclusion criterion, this study showed that 28% of all subjects had pathological resting 12-lead ECGs at rest and 35% had pathological heart rhythms when assessed by 24-h Holter ECG. At follow-up, 21% of females and 43% of males had presented with ECG abnormalities, and 30% of females and 36% of males had cardiovascular disease. There was hypertension in 45% of females and in 58% of males. However, no association was found between the follow-up findings and ECG changes seen at baseline. Conclusion: Although most ECG changes found at baseline could be considered as a normal variation, they may progress to more severe heart complications as the subject ages. The results of this study also validate ECG findings of previous studies and underline that diagnostic criteria should be based on gender and age.

Background Dynamic spirometry is an important investigation to differentiate between impaired and normal lung function, stressing the importance of selecting consistant and reliable clinical reference data. This study aims to evaluate the results of lung function testing in subjects without known heart or pulmonary disease living in Northern Sweden, with a focus on a comparison with previously published reference materials. Methods The study is based on 285 (148 males) healthy adults, 20-90 years of age. The subjects had been randomly selected and included in a study of cardiac function in heart-healthy subjects and were also assessed with dynamic spirometry, where 16 subjects presented with pulmonary functional impairments and were excluded. The sex-specific age-dependency in lung volumes was estimated using the LMS model, where non-linear equations are derived for the mean value (M), the location (L) or skewness, and the scatter (S) or coefficient of variation. A comparison was made with the reference values given by the original LMS model that is suggested by the Global Lung Initiative (GLI), and with the reference values from the recent Obstructive Lung Disease In Norrbotten (OLIN) study, which is also based on subjects from Northern Sweden. Results No differences were found in the age-dependency of pulmonary function between the new LMS model and the OLIN model. The original GLI reference values suggested significantly lower normal values, and consequently resulted in fewer subjects with both FEV1 and FVC values below the lower limit of normality, than both the new model and the OLIN model. Conclusions Our results are in line with previous reports and support that the original GLI reference values underestimate pulmonary function in the adult Swedish population. This underestimation could be reduced by updating the coefficients in the underlying LMS model with values that are specific for Swedish citizens. For optimal accuracy the final coefficients should be verified in a larger cohort.

Background Dynamic spirometry is an important investigation to differentiate between impaired and normal lung function. This study aimed to evaluate the results of lung function testing in a cohort of subjects from Northern Sweden without any known heart or pulmonary disease. Our focus was to compare with two reference materials that have showed differences in the age-dependency of lung function in Swedish subjects. Methods The study population consisted of 285 healthy adults (148 males, 52%) between 20–90 years of age. The subjects had been randomly selected from the population register for inclusion in a study investigating cardiac function in heart-healthy subjects, but were also assessed with dynamic spirometry. At least seven percent reported smoking. Sixteen subjects presented with pulmonary functional impairments and were excluded from the current study. The sex-specific age-dependency in lung volumes was estimated using the LMS model, where non-linear equations were derived for the mean value (M), the location (L) or skewness, and the scatter (S) or coefficient of variation. This model of the observed lung function data was compared with reference values given by the original LMS model published by the Global Lung Initiative (GLI), and with the model from the recent Obstructive Lung Disease In Norrbotten (OLIN) study, where higher reference values were presented for Swedish subjects than those given by the GLI model. Results No differences were found in the age-dependency of pulmonary function between the LMS model developed in the study and the OLIN model. Although the study group included smokers, the original GLI reference values suggested significantly lower normal values of FEV1 (forced expiratory volume) and FVC (forced vital capacity), and consequently fewer subjects below the lower limit of normality, than both the rederived LMS and OLIN models. Conclusions Our results are in line with previous reports and support that the original GLI reference values underestimate pulmonary function in the adult Swedish population. This underestimation could be reduced by updating the coefficients in the underlying LMS model based on a larger cohort of Swedish citizens than was available in this study.