Hypersynchronisme dans la cardiomyopathie hypertrophique sarcomérique : description et approche mécanistique avec une cartographie électro-mécanique non invasive multimodale

Abstract : Background: little is known about the left ventricular (LV) sequences of contraction and electrical activation in hypertrophic cardiomyopathy (HCM). A better understanding of the underlying relation between mechanical and electrical activation may allow the identification of predictive response criteria to right ventricular DDD pacing in obstructive patients. Objective: to describe LV mechanical and electrical activation sequences in HCM patients and compare them to a control group. Methods: we prospectively studied, in 40 HCM patients (20 obstructive and 20 non- obstructive) and 20 healthy controls, 1) mechanical activation with echocardiography at rest and during exercise, and cardiac magnetic resonance imaging, 2) electrical activation with 3- dimensional electrocardiographic mapping (ECM). Results: in echocardiography, healthy controls had a physiological apex-to-base delay (ABD) in contraction (23.8±16.2ms). Among the 40 HCM patients, 18 (45%) presented a loss of this ABD (ABD<10ms) defining hypersynchrony. These patients had lower LV end-diastolic volumes (71.4±9.7ml/m2 vs. 82.4±14.8ml/m2, p=0.01), lower native T1 values (988±32ms vs. 1028±39ms, p=0.001) and tended to have lower LV masses (80.7±23.7g/m2 vs. 94.5±25.3g/m2, p=0.08) compared with HCM patients having a physiological contraction sequence. There was no significant relation between ABD and LV outflow tract obstruction. While HCM patients with physiological contraction sequence presented ECM close to those encountered in controls, patients with loss of the ABD presented a particular pattern of ECM with the first potential more frequently occurring in the postero-basal region. Conclusion: the LV contraction sequence can be modified in HCM patients, with a loss of the physiological ABD (hypersynchrony). This phenomenon was associated with lower LV dimensions and native T1 values and a particular pattern of ECM but seemed to be independent of obstruction.
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Master Thesis
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Matthieu Michaud. Hypersynchronisme dans la cardiomyopathie hypertrophique sarcomérique : description et approche mécanistique avec une cartographie électro-mécanique non invasive multimodale. Médecine humaine et pathologie. 2018. ⟨dumas-02071539⟩

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