HETEROGENEITY OF HYPERTROPHY IN FELINE HYPERTROPHIC HEART-DISEASE

Eighty-six cats with non-dilated left ventricular myocardial hypertrop hy were studied retrospectively. Cats were categorized by two-dimensio nal echocardiography as having symmetric ventricular hypertrophy (Type I), asymmetric with predominant septal thickening hypertrophy (Type I I), and asymmetric hypertrophy with predominant free-wall thickening ( Type III). The distribution of hypertrophy was judged subjectively and objectively. Subjective and objective results were similar (P = 0.03) although overlap existed between groups. Morphologic patterns (Types I, II, and III) were compared with breed, age, sex, heart rate, percen t fractional shortening, left atrial size, serum creatinine concentrat ion, and the presence (yes/no) of pleural effusion, pulmonary edema, p ericardial effusion, heart murmur, dyspnea, thromboembolism, hyperthyr oidism, and being alive at the time of study. Interventricular septal thickness, left ventricular free wall thickness, percent fractional sh ortening, and left atrial size additionally were compared to 3-month s urvival. Cats with Type III hypertrophy were more likely to experience thromboembolism than cats with Type II hypertrophy (P = 0.05) and cat s with Type I hypertrophy were more likely to have heart murmurs than cats with Type III (P = 0.02). No other significant associations were found in comparison to pattern of hypertrophy. Both left atrial size a nd percent fractional shortening significantly correlated with 3-month survival (P < 0.001 for each). The degree of interventricular septal wall thickness was associated with 3-month survival (P = 0.02) when kn own hyperthyroid cats were excluded from the study group, while left v entricular free wall thickness consistently was not associated with su rvival. This study demonstrates the heterogeneity of hypertrophy in ca ts with hypertrophic heart disease and provides predictors of survival (left atrial size, percent fractional shortening, and interventricula r septal wall thickness when compared with euthanasia/spontaneous deat h data).