Tissue Doppler imaging in Maine Coon cats with a mutation of myosin binding protein C with or without hypertrophy.
BACKGROUND
The cardiac myosin binding protein C gene is mutated in Maine Coon (MC) cats with familial hypertrophic cardiomyopathy.


OBJECTIVE
Early diastolic mitral annular velocity is incrementally reduced from normal cats to MC cats with only an abnormal genotype to MC cats with abnormal genotype and hypertrophy.


METHODS
Group 1 consisted of 6 normal domestic shorthair cats, group 2 of 6 MC cats with abnormal genotype but no hypertrophy, and group 3 of 15 MC cats with hypertrophy and abnormal genotype.


METHODS
The genotype and echocardiographic phenotype of cats were determined, and the cats were divided into the 3 groups. Tissue Doppler imaging (TDI) of the lateral mitral annulus from the left apical 4-chamber view was performed. Five nonconsecutive measurements of early diastolic mitral annular velocity (EM) or summated early and late diastolic velocity (EAsum) and heart rate were averaged.


RESULTS
There was an ordered reduction in Em-EAsum as group number increased (group 1, range 9.7-14.7 cm/s; group 2, range 7.5-13.2 cm/s; group 3, range 4.5-14.1 cm/s; P = .001). Using the lower prediction limit for normal Em-EAsum, the proportion of cats with normal Em-EAsum decreased as the group number increased (P = .001). However, Em-EAsum was reduced in only 3 of 6 cats in group 2.


CONCLUSIONS
The incremental reduction of Em-EAsum as group severity increased indicates that diastolic dysfunction is an early abnormality that occurs before hypertrophy development. TDI measurement of Em or EAsum of the lateral mitral annulus is an insensitive screening test for identification of phenotypically normal, genotypically affected cats.
MacDonald
Kristin A
KA
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA. kamacdonald@ucdavis.edu
Kittleson
Mark D
MD
Kass
Philip H
PH
Meurs
Kathryn M
KM
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D002371:Cat Diseases / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D002415:Cats; D005260:Female; D020022:Genetic Predisposition to Disease; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D008297:Male; D009154:Mutation / Q000235:genetics*; D000099163:Myosin Binding Protein C
D002352:Carrier Proteins; D000099163:Myosin Binding Protein C