Clinical Research
Hypertrophic Cardiomyopathy
Assessment and Significance of Left Ventricular Mass by Cardiovascular Magnetic Resonance in Hypertrophic Cardiomyopathy

https://doi.org/10.1016/j.jacc.2008.04.047Get rights and content
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Objectives

Our aim was to assess the distribution and clinical significance of left ventricular (LV) mass in patients with hypertrophic cardiomyopathy (HCM).

Background

Hypertrophic cardiomyopathy is defined echocardiographically by unexplained left ventricular wall thickening. Left ventricular mass, quantifiable by modern cardiovascular magnetic resonance techniques, has not been systematically assessed in this disease.

Methods

In 264 HCM patients (age 43 ± 18 years; 75% men), LV mass by cardiovascular magnetic resonance was measured, indexed by body surface area, and compared with that in 606 healthy control subjects.

Results

The LV mass index in HCM patients significantly exceeded that of control subjects (104 ± 40 g/m2 vs. 61 ± 10 g/m2 in men and 89 ± 33 g/m2 vs. 47 ± 7 g/m2 in women; both p < 0.0001). However, values were within the normal range (≤ mean +2 SDs for control subjects) in 56 patients (21%), and only mildly increased (mean +2 to 3 SDs) in 18 (16%). The LV mass index showed a modest relationship to maximal LV thickness (r2 = 0.38; p < 0.001), and was greater in men (104 ± 40 g/m2 vs. 89 ± 33 g/m2 in women; p < 0.001) and in patients with resting outflow obstruction (121 ± 43 g/m2 vs. 96 ± 37 g/m2 in nonobstructives; p < 0.001). During a 2.6 ± 0.7-year follow-up, markedly increased LV mass index proved more sensitive in predicting outcome (100%, with 39% specificity), whereas maximal wall thickness >30 mm was more specific (90%, with 41% sensitivity).

Conclusions

In distinction to prior perceptions, LV mass index was normal in about 20% of patients with definite HCM phenotype. Therefore, increased LV mass is not a requirement for establishing the clinical diagnosis of HCM. The LV mass correlated weakly with maximal wall thickness, and proved more sensitive in predicting outcome.

Key Words

hypertrophic cardiomyopathy
cardiac magnetic resonance
left ventricular mass
hypertrophy
outcome

Abbreviations and Acronyms

BSA
body surface area
CMR
cardiovascular magnetic resonance
HCM
hypertrophic cardiomyopathy
LV
left ventricle/ventricular
OR
odds ratio

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Supported, in part, by grants from the Italian Ministry for Scientific and Technologic Research (PRIN 2006) and the Fondazione Ente Cassa di Risparmio di Firenze, Florence, Italy.