Cardiovascular determinants of QT interval duration in dysplipidemic patients in primary prevention in two genders

Aim: The aim was to investigate the relationship between rate corrected QT intervals in dyslipidemic patients in primary prevention (males vs. females) with the other major cardiovascular risk factors (age, SBP, DBP,BMI, LDL-C, HDL-C). Methods: 183 males and 222 females were investigated. Heart rate (HR) and QT intervals were measured automatically from resting ECGs. Six methods (Bazett, Fridericia, Hodges, Nomogram-Karjalainen, Rautaharju and Sagie-Framingham,) were used to correct the QT interval for HR. Exclusion criteria were: left or right bundle branch block, atrial fibrillation and use of medications affecting the QT intervals. Crude correlations (Spearman rank) between QT or QTcs with cardiovascular risk factors were examined. Linear regression analyses were performed to evaluate predominant determinants of QT. Results: In males statistically significant (p< 0.05 for Bazett and p< 0.01 for the other QTcs) crude correlations were found between QT or QTcs (B F,H, K, R and S-F) and age r=0.216 (corrected: 0.166-0.226-0.224-0.225-0.207-0.221).In females crude correlations were significant (p< 0.05) between QTcs (F, H, K) and age (r=0.139-0.150-0.137). We observed gender differences in the relationship betweenQT or QTcs with SBP. We found positive correlations in males for QTcs (B F,H, K, R and S-F) with SBP ( r=0.274-0.224-0.195-0.233-0.246-0.246; p< 0.01).Negative correlations were found in females (QT r= -0.190; p< 0.01 and QTc (H) r= -0.143;p< 0.05). In males after multiple linear regression analyses, age was the strongest predictor of QT (B= 0.062;p< 0.05), whereas SBP was the best determinant of QTc (Rautaharju B=0.343;p< 0.05). In females, age and SBP were significant independent variables for QT (B=0.612;-0.631;p< 0.01). Conclusions: QT measurements may provide additional diagnostic and prognostic information in dyslipidemic patients in primary prevention. However, the effect of cardiovascular risk factors seems to differ between males and females on QT interval duration