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Cardiac diagnostic… 2021 JVIM article

Title: Cardiac diagnostic test results and outcomes in 44 dogs naturally infected with Trypanosoma cruzi

Authors: Derek J. Matthews, Ashley B. Saunders, Alyssa C. Meyers, Sonya G. Gordon, and Sarah A. Hamer

Journal/Date of Publication: Journal of Veterinary Internal Medicine, 2021

DOI: 10.1111/jvim.16166 

Objective: To describe the cardiac diagnostic test results and outcomes of dogs naturally infected with T. cruzi.

Type of Study: Retrospective

Conclusions:

  1. ECG abnormalities were detected in 95% of the dogs, with ventricular arrhythmias (65%) and atrioventricular block (AVB, 33%) being common.
  2. Echocardiographic findings included right ventricular (RV) enlargement in 35% of dogs and left atrial enlargement in 29-49% depending on how measurements were obtained.
  3. Elevated cardiac troponin I (cTnI) concentrations were observed in 56% of dogs, indicating myocardial damage.
  4. Risk factors for cardiac-related death: RV enlargement, AVB, and high ventricular arrhythmia scores (modified Lown score ≥2) were associated with shorter survival times.

Clinical Application:

  1. ECG monitoring is critical for identifying arrhythmias and conduction abnormalities in T. cruzi-positive dogs.
  2. Ventricular arrhythmias (modified Lown score ≥2) and RV enlargement are strong indicators of poorer prognosis.
  3. Ambulatory ECG (Holter) can detect more severe arrhythmias missed by standard ECG.
  4. cTnI measurement can help assess myocardial damage, with high concentrations associated with heart damage.
  5. Echocardiography, particularly focusing on RV enlargement, provides prognostic information.
  6. Early identification of conduction abnormalities, such as AV blocks, provides evidence of infection.
  7. Close follow-up and comprehensive cardiac diagnostics (including ECG, echocardiography, cTnI) are useful tests when managing dogs with Chagas disease.
three-panel figure showing survival probability of dogs in study as described in caption
Figure 1. Kaplan-Meier survival curves for dogs seropositive for Trypanosoma cruzi. Each cross represents when a dog was censored and days are measured from first exam at a veterinary medical teaching hospital. Variables measured include, A, presence or absence of AV block, B, ventricular arrhythmias with modified Lown score (MLS) categorized as <2 or ≥2, and C, presence or absence of right ventricular (RV) enlargement. Only significant variables are shown.

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