Isovolumic Relaxation Time as an Indicator of Diastolic Dysfunction in Hypertrophic Cardiomyopathy


1 Echocardiography Research Center, Rajaie Cardiovascular, Medical, and Research Center, Iran University of Medical Sciences, Tehran, IR Iran.

2 Atherosclerosis Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran.


Background: Hypertrophic cardiomyopathy (HCM) is clinically characterized by the presence of left
ventricular hypertrophy in the absence of hypertension and valvular heart disease. Diastolic
dysfunction is an important pathology in patients with HCM, and it is characterized by
abnormal relaxation, increased left ventricular filling pressure, pulmonary congestion, and
ultimately cardiac symptoms. The present study aimed to assess the isovolumic relaxation time
(IVRT) in patients with HCM as an important indicator of diastolic dysfunction.
Methods: Nineteen control subjects and 35 patients with HCM were included in the present study.
Diagnosis was based on the confirmation of unexplained myocardial hypertrophy in the left
ventricle by conventional echocardiography. The peak velocity of early (E) and late (A) filling,
E-wave deceleration time (DT), and the E/A ratio were assessed using pulsed-wave Doppler
(PWD) echocardiography at the tip of the mitral valve leaflets in the apical 4-chamber view.
The IVRT was measured in the 4-chamber view via the PWD method. To that end, the filtering
gain of the images was adjusted and the IVRT was estimated.
Results: The mean age of the patients was 31±16 years. The IVRT more significantly increased in the
patients with HCM than in the control group (P<0.01). The IVRT rose more significantly in the
patients with no left ventricular outflow tract (LVOT) obstruction than in those with LVOT
gradients (97±38 vs 82±29; P<0.001). The mean septal thickness was 24±7 mm in the patients
with HCM, and increased septal thickness was significant in the patients who received
implantable cardioverter defibrillators (P<0.05).
Conclusions: The diastolic function was impaired in our patients with HCM. Moreover, the IVRT as a
noninvasive index of the diastolic function was prolonged in those with HCM.