Samanta Rahul, Kumar Saurabh, Chik William, Qian Pierre, Barry Michael A, Al Raisi Sara, Bhaskaran Abhishek, Farraha Melad, Nadri Fazlur, Kizana Eddy, Thiagalingam Aravinda, Kovoor Pramesh, Pouliopoulos Jim
From the Department of Cardiology, Westmead Hospital, New South Wales, Australia (R.S., S.K., W.C., P.Q., M.A.B., S.A.R., A.B., F.N., E.K., A.T., P.K., J.P.); and Sydney Medical School, University of Sydney, Australia (R.S., W.C., S.A.R., A.B., M.F., E.K., A.T., P.K., J.P.).
Circ Arrhythm Electrophysiol. 2017 Oct;10(10). doi: 10.1161/CIRCEP.116.004998.
Recent studies have demonstrated that intramyocardial adipose tissue (IMAT) may contribute to ventricular electrophysiological remodeling in patients with chronic myocardial infarction. Using an ovine model of myocardial infarction, we aimed to determine the influence of IMAT on scar tissue identification during endocardial contact mapping and optimal voltage-based mapping criteria for defining IMAT dense regions.
In 7 sheep, left ventricular endocardial and transmural mapping was performed 84 weeks (15-111 weeks) post-myocardial infarction. Spearman rank correlation coefficient was used to assess the relationship between endocardial contact electrogram amplitude and histological composition of myocardium. Receiver operator characteristic curves were used to derive optimal electrogram thresholds for IMAT delineation during endocardial mapping and to describe the use of endocardial mapping for delineation of IMAT dense regions within scar. Endocardial electrogram amplitude correlated significantly with IMAT (unipolar =-0.48±0.12, <0.001; bipolar =-0.45±0.22, =0.04) but not collagen (unipolar =-0.36±0.24, =0.13; bipolar =-0.43±0.31, =0.16). IMAT dense regions of myocardium reliably identified using endocardial mapping with thresholds of <3.7 and <0.6 mV, respectively, for unipolar, bipolar, and combined modalities (single modality area under the curve=0.80, <0.001; combined modality area under the curve=0.84, <0.001). Unipolar mapping using optimal thresholding remained significantly reliable (area under the curve=0.76, <0.001) during mapping of IMAT, confined to putative scar border zones (bipolar amplitude, 0.5-1.5 mV).
These novel findings enhance our understanding of the confounding influence of IMAT on endocardial scar mapping. Combined bipolar and unipolar voltage mapping using optimal thresholds may be useful for delineating IMAT dense regions of myocardium, in postinfarct cardiomyopathy.
近期研究表明，心肌内脂肪组织（IMAT）可能在慢性心肌梗死患者的心室电生理重塑中发挥作用。我们利用绵羊心肌梗死模型，旨在确定IMAT对心内膜接触标测期间瘢痕组织识别的影响以及用于定义IMAT致密区域的基于最佳电压的标测标准。
对7只绵羊在心肌梗死后84周（15 - 111周）进行左心室心内膜和透壁标测。采用Spearman等级相关系数评估心内膜接触电图振幅与心肌组织学组成之间的关系。使用受试者工作特征曲线得出心内膜标测期间用于描绘IMAT的最佳电图阈值，并描述心内膜标测在瘢痕内描绘IMAT致密区域的应用。心内膜电图振幅与IMAT显著相关（单极=-0.48±0.12，<0.001；双极=-0.45±0.22，=0.04），但与胶原蛋白无关（单极=-0.36±0.24，=0.13；双极=-0.43±0.31，=0.16）。心肌的IMAT致密区域可通过心内膜标测可靠识别，单极、双极和联合模式的阈值分别为<3.7和<0.6 mV（单模式曲线下面积=0.80，<0.001；联合模式曲线下面积=0.84，<0.001）。在IMAT标测期间，使用最佳阈值的单极标测在局限于假定瘢痕边界区（双极振幅，0.5 - 1.5 mV）时仍具有显著可靠性（曲线下面积=0.76，<0.001）。
这些新发现增强了我们对IMAT对心内膜瘢痕标测的混杂影响的理解。在心肌梗死后心肌病中，使用最佳阈值的联合双极和单极电压标测可能有助于描绘心肌的IMAT致密区域。
