Spectrum and Clinical Significance of Systolic Function and Myocardial Fibrosis Assessed by Cardiovascular Magnetic Resonance in Hypertrophic Cardiomyopathy

Abstract

In hypertrophic cardiomyopathy (HCM), the clinical significance attributable to the broad range of left ventricular (LV) systolic function, assessed as the ejection fraction (EF), is incompletely resolved. We evaluated the EF using cardiovascular magnetic resonance (CMR) imaging in a large cohort of patients with HCM with respect to the clinical status and evidence of left ventricular remodeling with late gadolinium enhancement (LGE). CMR imaging was performed in 310 consecutive patients, aged 42 +/- 17 years. The EF in patients with HCM was 71 +/- 10% (range 28% to 89%), exceeding that of 606 healthy controls without cardiovascular disease (66 +/- 5%, p <0.001). LGE reflecting LV remodeling showed an independent, inverse relation to the EF (B-0.69, 95% confidence interval -0.86 to -0.52; p <0.001) and was greatest in patients with an EF <50%, in whom it constituted a median value of 29% of the LV volume (interquartile range 16% to 40%). However, the substantial subgroup with low-normal EF values of 50% to 65% (n = 45; 15% of the whole cohort), who were mostly asymptomatic or mildly symptomatic (37 or 82% with New York Heart Association functional class I to II), showed substantial LGE (median 5% of LV volume, interquartile range 2% to 10%). This overlapped with the subgroup with systolic dysfunction and significantly exceeded that of patients with an EF of 66% to 75% and >75% (median 2% of the LV volume, interquartile range 1.5% to 4%; p <0.01). In conclusion, in a large cohort of patients with HCM, a subset of patients with low-normal EF values (50% to 65%) was identified by contrast-enhanced CMR imaging as having substantial degrees of LGE, suggesting a transition phase, potentially heralding advanced LV remodeling and systolic dysfunction, with implications for clinical surveillance and management.

Molecular consequences of the R453C hypertrophic cardiomyopathy mutation on human β-cardiac myosin motor function

“…6), in agreement with the results that we report here for R453C β-cardiac myosin. It has been noted that patients with HCM often have enhanced contractile function, measured echocardiographically as an increased left ventricular ejection fraction (LVEF) (24,25). Recent echocardiographic studies of patients harboring HCM-causing mutations in β-cardiac myosin who have no evidence of hypertrophy (so-called genotype positive/phenotype negative or preclinical HCM patients) demonstrate that these individuals also have increased LVEFs.…”

Myocardial energy depletion and dynamic systolic dysfunction in hypertrophic cardiomyopathy

“…Ejection fraction is normal or hyperdynamic in HCM, except infrequently in the 2% of patients who develop transformation into LV hypokinesia owing to diffuse fibrosis. 61 A disparity often exists between the macroscopic assessment of global ejection fraction in patients with HCM who have decreased diastolic volumes, and the more granular assessment of decreased systolic strain even at rest. Reduced systolic strain is commonly detected both with echocardiographic speckle-tracking and using cardiac MR in patients with HCM, and correlates with the extent of exercise impairment even in nonobstructed patients 41 .…”

“…Only 24% of patients had resting perfusion defects, and these patients had reduced resting systolic function owing to myocardial fibrosis in the end-stage phase of the disease 61 . Additionally, overall resting myocardial blood flow (assessed using PET and 13 N-labelled ammonia) did not differ between patients with HCM and controls (although the vasodilator 'reserve', assessed using dipyridamole, was blunted) 62 .…”

Clinical variants and outcomes of progressive chronic heart failure in individuals with hypertrphic cardiomyopathy

“…В нашей когорте пациентов с ГКМП при длительном наблюдении таких пациентов было 6,1 %. По данным предыдущих исследований, такая форма встречается у 15-20 % пациентов с ГКМП [14,16,18]. При опреде-лении этой стадии прогрессирования заболевания каж-дая из характеристик, таких как наличие ФВ ЛЖ в низ-ком или нормальном диапазоне [14], изменение диасто-лической функции от умеренной до выраженной [19], выраженная дилатация ЛП [17], увеличение области отсроченного конрастирования гадолинием [19], истон-чение стенки ЛЖ [13], эпизоды ФП [20,21], спонтан-ное снижение или утрата градиента выходного тракта ОРИГИНАЛЬНЫЕ СТАТЬИ § ЛЖ [22], описывались отдельно в когортах пациентов с ГКМП.…”