How to screen cats with heart murmurs for disease

Abstract

BACKGROUND: Heart murmurs can be present in both cats with asymptomatic cardiac disease and in cats with normal hearts. Echocardiography to detect cardiac disease might not be readily accessible to all owners. HYPOTHESIS/OBJECTIVES: Evaluate the accuracy of combined signalment, physical examination and cardiac biomarkers in screening cats with asymptomatic murmurs for cardiac disease. ANIMALS: Two hundred two cats with murmurs but no clinical signs of cardiac disease. METHODS: Single-center, cross-sectional study. All cats underwent echocardiography. Multivariable binary logistic regression identified variables independently associated with odds of cardiac disease. Data are presented as odds ratios (OR), area under the curve (AUC), and 95% confidence intervals (95% CIs). RESULTS: One hundred twenty-three cats (123/202, 60.9%) had cardiac disease; hypertrophic cardiomyopathy was most common (59/123, 48%). Few cats (24/202, 11.9%) had moderate-severe left atrial enlargement. N-terminal pro-brain natriuretic peptide (NT-proBNP) ≥ 109 pmol/L (OR 5.9; 95% CI, 2.6-14.1), body condition score ≥ 6/9 (OR 4.0; 95% CI, 1.6-11.6), murmur grade ≥ 3/6 (OR 3.6; 95% CI, 1.6-8.2) and male sex (OR 2.8; 95% CI, 1.2-6.6) were independently associated with odds of cardiac disease. The AUC for this 4-variable model (AUC 0.81; 95% CI, 0.74-0.88) was higher than that for the signalment and physical examination variables (AUC 0.74; 95% CI, 0.67-0.82) or NT-proBNP (AUC 0.73; 95% CI, 0.65-0.80) alone. The model's sensitivity in identifying cardiac disease was 86.5% (95% CI, 78.7%-91.8%); its specificity was 61.0% (95% CI, 48.3%-72.4%). CONCLUSIONS AND CLINICAL IMPORTANCE: Combining signalment, physical examination and NT-proBNP in cats with asymptomatic murmurs helps identify those with higher odds of cardiac disease, which could help select cats for echocardiography.