Which screening modalities and intervals are recommended for detecting HCM in cats?

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Echocardiography is the gold standard for feline HCM screening, but a multimodal approach combining physical examination, cardiac biomarkers, and imaging is recommended given the highly variable presentation of the disease. 67 Echocardiography remains the definitive diagnostic test for feline cardiomyopathy. Mild to moderate left ventricular (LV) wall thickening is a diagnosis of exclusion — hyperthyroidism, systemic hypertension, acromegaly, and dehydration must be ruled out before attributing LV hypertrophy to HCM. 7 Prevalence estimates using a ≥6 mm LV wall thickness cutoff range from 8.3% to 14.7% in general cat populations; studies using a ≥5.5 mm cutoff report 8.5% to 25% depending on breed. 12 Focused cardiac ultrasound by non-specialist practitioners is a recognized option for screening asymptomatic cats when specialist echocardiography is unavailable, though echocardiograms performed by board-certified cardiologists remain the clinical reference standard. 9 Cardiac troponin I (cTnI) is the most sensitive and specific blood-based screening test currently available. Using the Siemens ADVIA Centaur TnI-Ultra assay, a cutoff of >0.06 ng/mL distinguishes healthy cats from cats with HCM with 91.7% sensitivity and 95.4% specificity. For asymptomatic cats with HCM specifically, the same cutoff yields 87.8% sensitivity and 95.4% specificity. 2 A separate assay using a cutoff of 0.163 ng/mL achieves 100% specificity but only 62.0% sensitivity for distinguishing healthy cats from asymptomatic HCM cats without left atrial enlargement (LAE), limiting its utility as a screening tool. 10 A cutoff of 0.234 ng/mL on that same assay identifies cats in heart failure with 95.0% sensitivity and 77.8% specificity. 10 Elevated cTnI is not cardiac-specific — hyperthyroidism, hypertension, renal disease, and critical illness can all increase cTnI concentrations, and echocardiography is required to confirm the diagnosis. 52 N-terminal pro-B-type natriuretic peptide (NT-proBNP) is t