Bi-atrial strain analysis at different stages of atrial fibrillation
Y K Mao, J P Chen, M M Ma, Y Yang, Y H Wang, R H Jiang, C Y JiangAbstract
Background
Left atrial (LA) mechanical dysfunction associated with atrial fibrillation (AF) has been well studied. Whereas, how the occurrence and stages of AF affected right atrium (RA) function was poorly understood. Accordingly, we sought to characterize bi-atrial strain during different stages of AF in detail. Furthermore, we compared the ability of RA and LA mechanics in identifying patients with paroxysmal AF(PAF) without LA enlargement.
Methods
A total of 422 patients with AF referring for radiofrequency ablation were consecutively enrolled. Patients were categorized according to rhythm and stages of AF: persistent AF(PerAF) (n=194), paroxysmal AF during AF rhythm(PAF-AF)(n=52) and PAF during sinus rhythm(PAF-SR)(n=176) at the time of echocardiography. A control group of 60 individuals was included for comparison, if no cardiac pathology was detected. Using speckle-tracking echocardiography, LA reservoir strain(LASr), RA reservoir strain(RASr)and mechanical dispersion (MD) of LA and RA were measured in all patients. Mechanical dispersion was defined as the standard deviation of the time to peak positive strain corrected by R-R interval.
Results
Compared to the control group, AF patients exhibited significantly lower RA and LA strain parameters. A progressive decrease in bi-atrial mechanical function was seen as the stage of AF advanced to more persistent forms: RASr and RA MD, 41.4±8.9% and 4.2±2.0%(control), 35.3±9.2% and 6.7±4.1%(PAF-SR), 16.7±8.6% and 10.7±5.9 (PAF-AF) and 15±4.9% and 11.1±4.9% (PerAF); LASr and LA MD, 40.4±7.9% and 4.0±1.6% (control), 26.7±7.6% and 6.4±2.7% (PAF-SR), 12.8±4.6% and 8.8±3.0% (PAF-AF) and 10.7±3.9% and 9.3±3.2% (PerAF),P < 0.01). AF stages were independent determinants of RA and LA mechanics after adjusting for age,gender ,comobidities and conventional echo parameters. LASr, LA MD and RA MD, rather than RASr, were independently associated with PAF-SR with normal LA size (adjusted odds ratio: 0.87,1.50 and 1.33,respectively,all P<0.05). ROC analysis yielded similar discriminative ability for LASr (area under the curve (AUC): 0.79) , LA MD (AUC: 0.71) and RA MD (AUC: 0.70).
Conclusions
AF affected bi-atrial mechanical function independently, and more so if stage of AF has advanced to more persistent forms. In the presence of sinus rhythm, both LA strain parameters and RA mechanical dispersion could independently identify PAF without LA enlargement. However, RASr seems to be less beneficial in this regard.bi-atrial strainstatistical analysis