Detection of congestive heart failure by Doppler echocardiography in cats with hypertrophic cardiomyopathy

Abstract

Background: Left-sided congestive heart failure (CHF) is characterized by increased filling pressures and related Doppler echocardiographic (DE) filling patterns.

Hypothesis: Doppler echocardiographic variables of left ventricular filling derived from transmitral flow, pulmonary vein flow, and tissue Doppler can be used to detect CHF in cats with hypertrophic cardiomyopathy (HCM).

Animals: Forty-seven client-owned cats.

Methods: Prospective clinical cohort study. Cats underwent physical examination, thoracic radiography, analysis of N-terminal pro-brain natriuretic peptide (NT-proBNP), and transthoracic echocardiography and were divided into 3 age-matched groups: Group 1 (apparently healthy control), Group 2 (preclinical HCM), and Group 3 (HCM and CHF). Measured and calculated variables included respiratory rate, DE estimates, serum NT-proBNP concentration, and radiographic CHF score. Groups were compared using ANOVA, and receiver operating characteristic (ROC) curve and multivariate analyses were used to identify diagnostic cutoffs for the detection of CHF.

Results: Fifteen cats were in Group 1, 17 in Group 2, and 15 in Group 3. The ROC analysis indicated that the ratio of peak velocity of early diastolic transmitral flow to peak velocity of late diastolic transmitral flow (area under the curve [AUC], 1.0; diagnostic cutoff, 1.77; P = .001), ratio of left atrial size to aortic annular dimension (AUC, 0.91; diagnostic cutoff, 1.96; P = .003), left atrial diameter (AUC, 0.89; cutoff, 18.5 mm; P = .004), diastolic functional class (AUC, 0.89; cutoff, class 2; P = .005), respiratory (AUC, 0.79; cutoff, 36 breaths per minute [brpm]; P = .02), and the ratio of the peak velocity of fused early and late transmitral flow velocities to the peak velocity of the fused early and late diastolic tissue Doppler waveforms (AUC, 0.74; cutoff, 15.1; P = .05) performed best for detecting CHF.

Conclusions and clinical importance: Various DE variables can be used to detect CHF in cats with HCM. Determination of the clinical benefit of such variables in initiating treatments and assessing treatment success needs further study.

Keywords: NT-ProBNP; diastolic function; feline; respiration rate.

FIGURE 1

Scatter plots of respiratory rate, 2‐dimensional, and Doppler echocardiographic variables of left ventricular filling in 17 cats with occult HCM (Group 2) and 15 cats with congestive heart failure secondary to HCM (Group 3). Respiratory rate (median, 34 versus 48 brpm, P = .001); LAD (median, 14.78 versus 20.57, P < .001); E:A ratio (median, 0.81 versus 3.3, P < .001); class of LV diastolic function (D‐class, median, 1 versus 2, P < .05); IVRT (median, 59 versus 37 ms, P = .28), EAfus:E′A′fus (median 11.4 versus 17.6, P = .03), Adur:ARdur (median, 0.98 versus 0.69, P = .22), and E:E′ (median 14.34 versus 14.64, P = .90). The bars represent median and interquartile range. Bars are not present for the categorical variable (D‐class) or when there were less than 3 observations per group