Department of Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH.
Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL.
Am J Vet Res. 2022 Aug 2;83(10):ajvr.22.05.0076. doi: 10.2460/ajvr.22.05.0076.
To assess whether cardiac MRI or various biomarkers can be used to detect myocardial ischemia and fibrosis in dogs with cardiomegaly secondary to myxomatous mitral valve disease (MMVD).
6 dogs with cardiomegaly secondary to naturally occurring stage B2 MMVD being treated only with pimobendan with or without enalapril and 6 control dogs with no cardiac disease. All dogs were ≥ 5 years old with no systemic illness.
Serum cardiac troponin I and concentrations were measured, and dogs were anesthetized for cardiac MRI with ECG-triggered acquisition of native T1- and T2-weighted images. Gadolinium contrast was administered to evaluate myocardial perfusion and late gadolinium enhancement (LGE). Mean T1 and T2 values and regions of LGE were measured with dedicated software. Extracellular volume (ECV) was estimated on the basis of Hct and T1 values of myocardium and surrounding blood. Subjective analysis for myocardial perfusion deficits was performed.
Dogs with MMVD had significantly (P = .013) higher cardiac troponin I concentrations than control dogs, but galectin-3 concentrations did not differ (P = .08) between groups. Myocardial fibrosis was detected in 4 dogs with MMVD and 3 control dogs; no dogs had obvious myocardial perfusion deficits. Native T1 and T2 values, postcontrast T1 values, and ECV values were not significantly different between groups (all P > .3).
Results suggest that some dogs with cardiomegaly secondary to MMVD may not have clinically relevant myocardial fibrosis.
评估心脏 MRI 或各种生物标志物是否可用于检测继发于黏液样变性二尖瓣疾病（MMVD）的心肌扩大犬的心肌缺血和纤维化。
6 只继发于自然发生的 B2 期 MMVD 的心肌扩大犬，仅接受匹莫苯丹和（或）依那普利治疗，6 只无心脏病的对照犬。所有犬均≥5 岁，无全身性疾病。
测量血清心肌肌钙蛋白 I 和浓度，并对犬进行心脏 MRI 麻醉，采用 ECG 触发采集原生 T1 和 T2 加权图像。给予钆造影剂以评估心肌灌注和延迟钆增强（LGE）。使用专用软件测量平均 T1 和 T2 值和 LGE 区域。根据心肌和周围血液的 Hct 和 T1 值估算细胞外容积（ECV）。进行主观分析以评估心肌灌注缺损。
MMVD 犬的心肌肌钙蛋白 I 浓度明显高于对照组犬（P =.013），但半乳糖凝集素-3 浓度在两组间无差异（P =.08）。4 只 MMVD 犬和 3 只对照犬检测到心肌纤维化；无犬存在明显的心肌灌注缺损。原生 T1 和 T2 值、对比后 T1 值和 ECV 值在两组间无显著差异（均 P >.3）。
结果提示，一些继发于 MMVD 的心肌扩大犬可能没有临床相关的心肌纤维化。
