Retrospective evaluation of the utility of shock index to determine the presence of congestive heart failure in dogs with myxomatous mitral valve disease (2019-2021): 98 cases.

Abstract

OBJECTIVES: To calculate the shock index (SI) in dogs with myxomatous mitral valve disease (MMVD) and to evaluate its use to predict the presence of congestive heart failure (CHF). DESIGN: Retrospective study. SETTING: Small animal university veterinary teaching hospital. ANIMALS: Ninety-eight dogs with MMVD and 20 healthy dogs as part of a control group. INTERVENTIONS: Heart rate (HR) and systolic blood pressure (SBP) were recorded, and SI was calculated by dividing HR by SBP for each dog. MEASUREMENTS AND MAIN RESULTS: The mean (SD) HR, SBP, and SI were 123/min (32.6), 147&#xa0;mm&#xa0;Hg (21.5), and 0.86 (0.3), respectively, for dogs with MMVD and 98/min (20.9), 145&#xa0;mm&#xa0;Hg (18.7), and 0.68 (0.13), respectively, for control dogs. Dogs with MMVD had a significantly higher HR compared with control dogs (P&#xa0;<&#xa0;0.01), and an elevation in HR was seen as the severity of MMVD increased. Dogs in stage B2 and C/D MMVD had a significantly higher SI value compared with control dogs (P&#xa0;=&#xa0;0.04 and P&#xa0;<&#xa0;0.01, respectively). SI was significantly higher in dogs in stage C/D MMVD compared with dogs in stage B2 MMVD (P&#xa0;<&#xa0;0.01). Ten of 98 (10%) dogs had an arrhythmia. HR, SBP, and SI were not significantly different between dogs with and without arrhythmias (P&#xa0;=&#xa0;0.13, P&#xa0;=&#xa0;0.57, and P&#xa0;=&#xa0;0.07, respectively), but significantly more dogs with CHF had an arrhythmia (P&#xa0;=&#xa0;0.01). SI (area under the curve [AUC]: 0.98) and HR (AUC: 0.95) were excellent indicators for the presence of CHF. An optimal SI cutoff value &#x2265;1.1 had 92% sensitivity and 95% specificity for predicting the presence of CHF, and an optimal HR cutoff value of &#x2265;157/min had 92% sensitivity and 93% specificity for the prediction of CHF. CONCLUSIONS: When there are compatible clinical signs, SI values &#x2265;1.1 may suggest the presence of CHF in dogs with MMVD.