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Abstract Background Predicting progression of myxomatous mitral valve disease (MMVD) in dogs can be challenging. Hypothesis/Objectives The mitral regurgitation severity index (MRSI) will predict time to congestive heart failure (CHF) and all‐cause death in dogs with MMVD. Animals Eight hundred sixty‐nine client‐owned dogs. Methods Retrospective study pooling data from 4 previous samples including dogs with MMVD stage B2 or C. MRSI was calculated as: (heart rate [HR]/120) × left atrium‐to‐aorta ratio (LA:Ao) × (age in years/10) × 100. Alternative MRSI formulas substituting radiographic measures of left atrial size were also calculated. Cox proportional hazard modeling and time‐dependent receiver‐operator characteristic curves quantified prognostic performance. Results For Stage B2 pooled samples, MRSI > 156 was predictive of time to CHF (median 407 vs 1404 days; area under the curve [AUC] 0.68; hazard ratio 3.02 [95% CI 1.9‐4.9]; P 173 was predictive of all‐cause death (median survival 868 vs 1843 days; AUC 0.64; hazard ratio 4.26 [95% CI 2.4‐7.5]; P

Background: Predicting progression of myxomatous mitral valve disease (MMVD) in dogs can be challenging. Hypothesis/Objectives: The mitral regurgitation severity index (MRSI) will predict time to congestive heart failure (CHF) and all‐cause death in dogs with MMVD. Animals: Eight hundred sixty‐nine client‐owned dogs. Methods: Retrospective study pooling data from 4 previous samples including dogs with MMVD stage B2 or C. MRSI was calculated as: (heart rate [HR]/120) × left atrium‐to‐aorta ratio (LA:Ao) × (age in years/10) × 100. Alternative MRSI formulas substituting radiographic measures of left atrial size were also calculated. Cox proportional hazard modeling and time‐dependent receiver‐operator characteristic curves quantified prognostic performance. Results: For Stage B2 pooled samples, MRSI > 156 was predictive of time to CHF (median 407 vs 1404 days; area under the curve [AUC] 0.68; hazard ratio 3.02 [95% CI 1.9‐4.9]; P <.001). MRSI > 173 was predictive of all‐cause death (median survival 868 vs 1843 days; AUC 0.64; hazard ratio 4.26 [95% CI 2.4‐7.5]; P <.001). MRSI showed superior predictive value compared to the individual variables of HR, LA:Ao, and age. Variations of the MRSI equation substituting radiographic vertebral left atrial size for LA:Ao were also significantly predictive of outcome in stage B2. MRSI was not consistently predictive of outcome in Stage C. Conclusions and Clinical Importance: MRSI was predictive of outcome (onset of CHF and all‐cause death) in MMVD Stage B2, demonstrating utility as a useful prognostic tool. Echocardiographic LA:Ao can be effectively replaced by radiographically determined LA size in the MRSI formula. [ABSTRACT FROM AUTHOR]

Background: Evaluation of left heart size helps determine disease severity in dogs with myxomatous mitral valve disease (MMVD). Hypothesis/Objectives: Determine the ability of radiographic vertebral heart size (VHS) and vertebral left atrial size (VLAS) to predict LHEECHO in dogs with preclinical MMVD. Animals Seventy client‐owned dogs with MMVD and no historical or present clinical or radiographic evidence of congestive heart failure (CHF). Methods: Retrospective cross‐sectional study of dogs with same‐day echocardiography and thoracic radiography. Receiver‐operating characteristic (ROC) curves were used to assess the ability of VHS, VLAS, and VHS + VLAS to discern dogs with and without LHEECHO, and clinically relevant cutpoints for these radiographic measurements were selected. Results: The ability of VHS and VHS + VLAS to predict LHEECHO was moderate (area under the curve [AUC]VHS = 0.851; 95% CI, 0.762‐0.941; AUCVHS + VLAS = 0.865; 0.783‐0.947), and performance of VLAS and VHS + VLAS was not different from that of VHS alone. A VHS cutpoint of >10.8 had sensitivity = 91.1% (76.3%‐98.1%) and specificity = 69.4% (51.9%‐83.7%) for predicting LHEECHO. A cutpoint of >11.7 had sensitivity = 32.4% (17.4%‐50.5%) and specificity = 97.2% (85.5%‐99.9%) for predicting LHEECHO. Thirty (43%) of the 70 dogs had a VHS value of 10.9 to 11.7. Conclusions and Clinical Importance: Vertebral heart size >11.7 identified dogs with LHEECHO and VHS ≤ 10.8 excluded dogs with LHEECHO. A large percentage of dogs had VHS values intermediate to these cutpoints. [ABSTRACT FROM AUTHOR]