Increased hs-CRP and decreased 1,25-dihydroxyvitamin D are associated with increased left ventricle lead threshold

There are not enough data about threshold changes in patients with CRT. In this study, we aimed to investigate frequency of significant threshold increase of left ventricle lead and to determine clinical, demographic, medical and laboratory parameters that associated with threshold increase in CRT implanted patients.

We included CRT implanted 200 patients (124 males, 76 females; mean age 65.8 ± 10.3 years) to this study. Basal and third month LV R wave amplitude, electrode impedance, and threshold values were recorded. Threshold increase was accepted as ≥0.1 V and significant increase as >1 V. Patients were divided into two groups: increased threshold and non-increased threshold for LV lead.

Number of patients with increased LV threshold was 68 (37.6 %). Furthermore, 8 % of patients had severe increase (≥1 V) in LV threshold. We observed that serum levels of hs-CRP and 1,25 (OH)2 vitamin D were independently associated with increased LV threshold. We showed that 1 mg/dl increase in hs-CRP and the 1 mg/dl decrease in vitamin D are associated with 25.3 and 4.5 % increase in the odds of increased LV threshold, respectively.

Increased hs-CRP and decreased 1,25 (OH)2 vitamin D are the strongest predictors of increased LV lead thresholds. We suggest that hs-CRP and 1,25 (OH)2 vitamin D may be used as markers to predict and follow the patients with increased thresholds. It may be useful to finalize CRT procedure with more appropriate basal threshold in patients with high serum hs-CRP and low 1,25 (OH)2 vitamin D levels.