Association between septal strain rate and histopathology in symptomatic hypertrophic cardiomyopathy patients undergoing septal myectomy.

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is histopathologically characterized by myocyte hypertrophy, disarray, interstitial fibrosis, and small intramural coronary arteriole dysplasia, which contribute to disease progression. Longitudinal systolic and early diastolic strain rate (SR) measurements by speckle tracking echocardiography are sensitive markers of regional myocardial function. We sought to determine the association between septal SR and histopathologic findings in symptomatic HCM patients who underwent surgical myectomy.

METHODS

We studied 171 HCM patients (documented on histopathology) who underwent surgical myectomy to relieve left ventricular outflow tract obstruction. Various clinical and echocardiographic parameters were recorded. Segmental longitudinal systolic and early diastolic SRs (of the septal segment removed at myectomy) were measured from apical 4- and 2-chamber views (VVI 2.0; Siemens, Erlangen, Germany). Histopathologic myocyte hypertrophy, disarray, small intramural coronary arteriole dysplasia, and interstitial fibrosis were classified as none, mild (1%-25%), moderate (26%-50%), and severe (>50%).

RESULTS

The mean age was 53 ± 14 years (52% men, ejection fraction 62% ± 5%, mean left ventricular outflow tract gradient 102 ± 39 mm Hg, and basal septal thickness of 2.2 ± 0.5 cm). Mean longitudinal systolic and early diastolic SRs were -0.91 ± 0.5 and 0.82 ± 0.5 (1/s), respectively. There was an inverse association between systolic and early diastolic septal SR and degree of myocyte hypertrophy, disarray, and interstitial fibrosis (all P < .05). There was no association between histopathologic characteristics and other echocardiography parameters. On multivariable regression analysis, myocyte disarray and echocardiographic septal hypertrophy were associated with systolic and early diastolic septal SR (P < .05).

CONCLUSION

In HCM patients, there is inverse association between various histopathologic findings and septal SR. Strain rate might potentially provide further insight into HCM pathophysiology.