Introduction: Hypertrophic cardiomyopathy (HCM), a genetic disease of cardiac sarcomere, has varied clinical presentation. Speckle tracking echocardiography (STE) is being increasingly used in HCM and there is data that global longitudinal strain (GLS) abnormalities on STE correlate with cardiac magnetic resonance (CMR) abnormalities which have a proven prognostic significance. There is lack of such data on Indian HCM patients.

 

Objectives: 1) To evaluate the clinical and imaging profile of HCM patients in India. 2) To correlate speckle tracking echo abnormalities with late gadolinium enhancement (detected on CMR) and electrocardiographic abnormalities detected by 24-hour Holter study.

 

Methods: After informed written consent, enrolled patients underwent detailed 2D-transthoracic echocardiography (TTE) including GLS imaging and 24-hr Holter monitoring. CMR was done in approximately half of the enrolled patients, based on treating cardiologist’s discretion.

 

Results: We enrolled 150 HCM patients from February 2022 to July 2023. All patients underwent TTE and Holter, while CMR was done in 74 patients. The mean age of patients was 46.7 years (SD 13.6) and 80% were males. Exertional dyspnea was present in 72%, angina in 48% and history of syncope in 21% cases. Majority of the patients were in New York Heart Association (NYHA) functional class II (70%) followed by NYHA I (18.6%) and NYHA III (11.3%). A positive family history in the form of either a known relative with confirmed HCM or sudden death (possibly related to HCM) was present in 10.6% of patients. Atrial fibrillation (paroxysmal or persistent) was diagnosed in 11.3% of the enrolled cases. Non sustained ventricular tachycardia (NSVT) runs were present in 21 (14%) patients on Holter.

 

The most common HCM phenotype was asymmetric septal hypertrophy (76%). Concentric left ventricular hypertrophy was present in 10.6% while a diagnosis of apical HCM was made in 12.7% patients. 53% of patients had significant left ventricular outflow tract obstruction (LVOTO), with continuous wave doppler gradients of ³ 30 mmHg either at rest or with provocation. Systolic anterior motion of anterior mitral leaflet (AML) was present in 90 (60%) cases. Mitral regurgitation was present in 80 (53.3%) of the cases which was mild in majority of the cases (70 cases or 46.7%). Tissue doppler data was available in 136 (90.6%) patients. Using a cut-off value of 7cm/s for medial e’ and 10cm/s for lateral e’, the medial e’ was reduced in 126 (92.6%) cases and lateral e’ was reduced in 130 (95.6%) cases. The peak left ventricular global longitudinal strain (GLS) was available in 126 patients. The mean value of peak GLS was - 12.1 % (SD 4.1) with values ranging from -4% to -24%. The average value of peak GLS in non-obstructive HCM was -12.7% as compared to -11.4% in the obstructive HCM group. However, this difference was not statistically different with a p value of 0.08).

 

Cardiac MRI data was available in 74 (49.3%) patients. Perfusion deficit was noted in hypertrophied segments in 19 (25.6%) cases. Any late gadolinium enhancement (LGE) was present in 68 patients i.e., 92% of patients who underwent CMR. LGE was ³ 15% of LV myocardium in 30 (40%) patients.

 

There was a significant correlation of peak GLS with percent LGE on CMR with a  Spearman’s correlation coefficient of 0.739. The mean peak GLS value in patients without NSVT was -12.3% as compared to the patients with NSVT -10.9%, however the difference was not statistically significant with a p value of 0.18 by two-sided T test.

 

Conclusion: This is the first study reporting such data on clinical and imaging profile of HCM patients in India. The most common phenotype is asymmetric septal hypertrophy and LGE is detected in majority of HCM patients. GLS abnormalities correlate with percent LGE which in turn is an established risk factor for sudden death in HCM.