| Objective To quantitatively evaluate the left atrial(LA)strain and strain rate in patients with hypertrophic cardiomyopathy(HCM)by cardiovascular magnetic resonance tissue tracking(CMR-TT),and to explore its clinical value in evaluating LA function.Material and Method From December 2009 to September 2017,50 patients with obstructive HCM(obstructive group),54 patients with non-obstructive HCM(non-obstructive group)and 28 healthy volunteers(control group)were analyzed retrospectively.All participants underwent CMR examinations with fast imaging employing steady state acquisition(FIESTA)cine sequence.The scan layer included left ventricular short axis,two and four chamber long axis.CVI42 was used to calculate the LA parameters,including LA strain(total strain [εs],passive strain [εe],active strain [εa]),strain rate(peak positive strain rate [SRs],peak early negative strain rate [SRe],peak late negative strain rate [SRa]),volume parameters(maximum of LA volume [LAVmax],minimum of LA volume [LAVmin],the volume before LA contraction [LAVpre])and LA emptying fraction(LA emptying fraction [LATEF],passive LA emptying fraction[LAPEF],active LA emptying fraction[LAAEF]).There are also some left ventricular function related indicators,including LVEDV,LVESV,SV,LVEF.According to the results of 24-hour ECG examination,the patients were divided into those with atrial premature beat(APB)and without it.Univariate analysis of variance and independent sample t-test were used to compare strain and volume parameters between groups,and univariate and multivariate logistic regression analysis was used to analyze the correlation between indexes and the incidence of APB.The ROC curve was used to analyze the diagnostic efficacy of observations on APB.Result The indexes of HCM patients were lower than the control group.The differences in εs,εe,εa,SRs,SRe and SRa between the obstruction group,non-obstruction group and the control group were statistically significant(all P <0.05),showing an increasing trend.(εs [%]:17.7±6.0 vs 21.8±7.1 vs 30.4±7.8;εe [%]:8.6±4.3 vs 11.0±5.8 vs 17.2±5.6;εa [%]:9.1±3.7 vs 10.8±3.2 vs 13.3±3.5;SRs [s-1]:0.86±0.3 vs 0.99±0.4 vs 1.31±0.3;SRe [s-1]:-0.75±0.2 vs-0.89±0.3 vs-1.76±0.4;SRa [s-1]:-0.82±0.3 vs-1.02±0.4 vs-1.36±0.3).The differences in LAVmin,LAVmax and LAVpre between the three groups were statistically significant(all P <0.05),showing a decreasing trend.(LAVmin[ml/m2]:49.7±18.8 vs 39.7±13.3 vs 19.0±6.1;LAVmax[ml/m2]:100.7±26.2 vs 89.9±16.0 vs 59.5±13.5;LAVpre[ml/m2]: 80.3±22.1 vs 68.6±14.5 vs 41.1±11.0).The differences in LATEF and LAPEF between three groups were statistically significant(both P <0.05),showing an increasing trend.(LATEF [%]:51.3±10.4 vs 56.4±10.5 vs 68.3±5.4;LAPEF[%]:20.3±6.9 vs 23.9±7.5 vs 30.4±12.4).While there was no statistical difference in LAAEF[%]between the obstruction and non-obstruction groups,they were 47.9 ± 9.6 vs 51.6 ± 12.0 vs 63.8 ± 6.4.The incidence of APB in the obstruction group was significantly higher than non-obstruction group(p <0.01).Multivariate analysis demonstrated that εs was an independent predictor of APB(odds ratio 0.85;p<0.01).The optimal cut-off value for εs in the diagnosis of APB was 20.25% with a sensitivity of 80.0% and specificity of 79.7%.The analysis of LA strain and strain rate parameters showed good consistency and reproducibility on an intra-observer and inter-observer level.Conclusion CMR-TT is a promising approach in detection of atrial performance and physiology by quantitatively assessing LA function.Abnormal LA function was observed in HCM patients,and meanwhile,the HOCM group is more severely impaired than NOHCM patients.Moreover,our results indicated that εs is an important risk factor for the APB occurrence in HCM and meanwhile provides prediction,prognosis and treatment guidance for HCM patients. |
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