Subclinical hyperthyroidism is not associated with progression of cardiac mass and development of left ventricular hypertrophy in middle-aged and older subjects: results from a 5-year follow-up.

BACKGROUND

Decreased serum TSH levels are associated with increased cardiovascular mortality in elderly, and subclinical hyperthyroidism (SCH) was associated with left ventricular hypertrophy (LVH) as a predictor of cardiovascular mortality in some cross-sectional and case-control studies. The aim was to assess whether SCH independently impacts development of LVH over time.

METHODS

Of 3300 participants of the population-based Study of Health in Pomerania those with overt hyperthyroidism, hypothyroidism, possible thyroid disease or missing echocardiographic baseline data or follow-up were excluded, resulting in a study population of 1112 individuals (556 women) aged 45-81 years. Echocardiographic left ventricular mass divided by height(2·7) (LVMI(ht)), and LVH(ht) (LVMI(ht) > 44 g/m(2·7) in women and > 48 g/m(2·7) in men) was measured at baseline and after 5-year follow-up (median 5·00; range 4·92; 5·08). Comparison of subjects with (n = 107) and without (n = 1005) SCH were made by linear and logistic regression models adjusted for age, gender, smoking status, hypertension, and waist circumference.

RESULTS

At follow-up, LVMI(ht) did not differ between subjects with and without SCH (50·2 g/m(2·7), interquartile range (IQR) 41·2; 59·5 vs 47·8 g/m(2·7), IQR 39·3; 56·9; P = 0·29). LVH(ht) was present in 66 (61·7%) subjects with and 543 (54·0%) persons without SCH (P = 0·13). Analyses revealed no association between SCH and progression of LVMI(ht) (β = -0·18; 95%-confidence interval (CI) -2·34; -1·99; P = 0·873), and development of LVH(ht) (relative risk 0·86, 95%-CI 0·60; 1·26; P = 0·462), respectively.

CONCLUSIONS

In this population-based sample, SCH had no impact on progression of LVMI and development of LVH during 5-year follow-up in subjects aged 45 years or older.