Stepien Rebecca L, Rak Mariola B, Blume Lauren M
J Am Vet Med Assoc. 2020 May 15;256(10):1129-1136. doi: 10.2460/javma.256.10.1129.
To investigate the usefulness of radiographic measures of the left atrium and ventricle as surrogates for echocardiographic criteria in identifying dogs with stage B2 preclinical myxomatous mitral valve disease (MMVD).
56 client-owned dogs with preclinical mitral regurgitation attributed to MMVD examined between April 19, 2016, and November 22, 2017.
Medical records were retrospectively searched, and data collected included age, body weight, heart murmur grade, and echocardiographic and radiographic measurements. Dogs were grouped according to whether they did (case dogs) or did not (control dogs) meet echocardiographic criteria used to identify dogs with stage B2 MMVD. Measurements for lateral thoracic radiographic variables normalized to vertebral body units (VBUs) were obtained, and results were analyzed to identify variables that could best discriminate between case and control dogs.
Three radiographic variables of left atrial size (vertebral left atrial size [VLAS], left atrial width, and the combined variable of VLAS + left atrial width) most accurately distinguished control dogs from case dogs, and the VLAS was the simplest and fastest to perform in a clinical setting. The optimal cutoff for VLAS was 2.5 VBUs (sensitivity, 70%; specificity, 84%; and likelihood ratio, 4.38), with VLAS ≥ 2.5 VBUs for case dogs. The maximum specificity cutoff for VLAS was 3.0 VBUs (sensitivity, 40%; specificity, 96%; and likelihood ratio, 10.0), with VLAS ≥ 3.0 VBUs for case dogs.
Results indicated that when echocardiography is unavailable, radiographic VLAS ≥ 3 VBUs could be used with minimal risk of false-positive diagnosis of stage B2 MMVD in dogs.
研究左心房和心室的X线测量指标作为超声心动图标准的替代指标，用于识别处于B2期临床前黏液瘤性二尖瓣疾病（MMVD）犬的有效性。
2016年4月19日至2017年11月22日期间检查的56只因MMVD导致临床前二尖瓣反流的客户拥有犬。
对病历进行回顾性检索，收集的数据包括年龄、体重、心脏杂音分级以及超声心动图和X线测量结果。根据犬是否符合用于识别B2期MMVD犬的超声心动图标准进行分组（病例犬和对照犬）。获取归一化为椎体单位（VBU）的侧位胸部X线变量测量值，并分析结果以确定最能区分病例犬和对照犬的变量。
左心房大小的三个X线变量（椎体左心房大小[VLAS]、左心房宽度以及VLAS +左心房宽度的组合变量）最准确地区分了对照犬和病例犬，且VLAS在临床环境中操作最简单、最快。VLAS的最佳截断值为2.5 VBU（敏感性，70%；特异性，84%；似然比，4.38），病例犬的VLAS≥2.5 VBU。VLAS的最大特异性截断值为3.0 VBU（敏感性，40%；特异性，96%；似然比，10.0），病例犬的VLAS≥3.0 VBU。
结果表明，当无法进行超声心动图检查时，X线VLAS≥3 VBU可用于犬B2期MMVD假阳性诊断风险最小。
