The cardiac isovolumetric contraction time is an independent predictor of incident atrial fibrillation and adverse outcomes following first atrial fibrillation event in the general population

Abstract

Colour tissue Doppler imaging (TDI) M-mode through the mitral leaflet is an easy and precise method to obtain cardiac time intervals including the isovolumic contraction time (IVCT), isovolumic relaxation time (IVRT), and ejection time (ET). The myocardial performance index (MPI) was defined as [(IVCT + IVRT)/ET]. Our aim was to investigate if cardiac time intervals can be used to predict atrial fibrillation (AF) in the general population. A total of 1915 participants from the general population underwent a health examination including TDI echocardiography. The primary endpoint was AF, and the secondary endpoint was complicated AF as assessed by the occurrence of either stroke or heart failure (HF) after the diagnosis of AF. Participants with known AF were excluded (n = 54). During a median follow-up of 11 years, 166 participants (9%) were diagnosed with AF and of these 44 participants (27%) developed HF or stroke. Assessing the association between IVCT and incident AF, the risk increased with 27% per 10 ms increase in IVCT [per 10 ms increase: hazard ratio (HR) 1.27, 95% confidence interval (CI) (1.17-1.38); P < 0.001]. The association remained significant after multivariable adjustment [per 10 ms increase: HR 1.22, 95% CI (1.09-1.35); P < 0.001]. No associations between the IVRT, ET, MPI, and AF remained significant after multivariable adjustment. The IVCT also predicted complicated AF and the association remained significant even after multivariable adjustment [per 10 ms increase: HR 1.39, 95% CI (1.06-1.81); P = 0.015]. In the general population, the IVCT provides novel and independent prognostic information on the long-term risk of AF. Additionally, the IVCT can identify persons in risk of complicated AF.