Abstract
OBJECTIVE: PTH influences atrial fibrillation (AF) risk factors and pathways involved in AF. We therefore sought to determine if PTH levels are altered in patients with AF. BACKGROUND: In addition to the traditional role of parathyroid hormone (PTH) as a regulator of calcium homeostasis, PTH also acts as a cardiac hormone, vasodilatory substance, and regulator of smooth muscle proliferation. METHODS: We compared plasma PTH levels in subjects with early-onset AF (n=230; 144 with lone AF and 86 with AF and hypertension), and control subjects (n=150). Subjects with structural heart disease were excluded. Plasma PTH levels were determined using a commercially available immunoassay. RESULTS: PTH levels were higher in subjects with early-onset AF versus controls (56 versus 50 pg/ml, p=0.01), and there was a stepwise increase in PTH levels from controls, to lone AF and AF and hypertension (50, 54 and 59 pg/ml, p=0.03). PTH levels were higher in permanent AF compared to paroxysmal AF (61 versus 55 pg/ml, p=0.03). PTH levels were higher in subjects with AF compared to sinus rhythm at the time of blood draw (64 versus 54 pg/ml, p=0.001). In a multivariable analysis, each mm increase in left atrial size was associated with a 0.005 (±0.002) pg/ml increase in log(PTH) levels (p=0.047). CONCLUSIONS: We demonstrate that PTH levels are higher in AF subjects, most prominently in subjects with hypertension and in AF at blood sampling. These data suggest that both the rhythm itself and hypertension, as a concomitant condition, may influence the relation between PTH and AF.