What is the clinical evidence from this study?

Study design: Case-Control. Population: Hypertrophic cardiomyopathy (n=50). Intervention: Two-dimensional echocardiography vs. Normal age-matched controls. Primary outcome: Left atrial mass (p=<0.0001).

May 30, 2007Open Access

An integrated approach to determine left atrial volume, mass and function in hypertrophic cardiomyopathy by two-dimensional echocardiography

Q: What are the key findings of this study?

Hypertrophic cardiomyopathy patients had significantly higher left atrial mass (89.8 g vs 32.3 g) and augmented left atrial pump function compared to normal controls.

Key Result

Hypertrophic cardiomyopathy patients had significantly higher left atrial mass (89.8 g vs 32.3 g) and augmented left atrial pump function compared to normal controls.

Study Design

Type

Case-Control (n=50)

PICO

Population

Hypertrophic cardiomyopathy (n=50)

Intervention / Comparator

Two-dimensional echocardiography vs Normal age-matched controls

Primary Outcome

Left atrial mass, p=<0.0001

Main Result

Absolute Event Rate: 89.8% vs 32.3%

p-value: p=<0.0001

Limitations

Small sample size of HCM patients (n=25) due to low disease prevalence
Assessment of LA mass by this formula needs validation by autopsy or magnetic resonance imaging
Assessment of diastolic dysfunction relied only on transmitral flow by pulsed wave Doppler without tissue Doppler imaging
Lack of long-term follow-up data to determine the prognostic value of atrial remodeling for developing atrial fibrillation

Abstract

METHODS: The study included 25 hypertrophic cardiomyopathy (HCM) patients (15 non-obstructive and 10 obstructive) and 25 controls for assessment of left atrial (LA) volume, mass and function by two-dimensional echocardiography. Measurement included mean LA diameter (LAD), LA mass = (mean LAD + anterior LA wall + posterior LA wall) 3 - mean LAD3 x 0. 8 + 0. 6, LA volume = (8/3 pi L. A1. A2), where L is LA length, A1 and A2 are LA area in 4-chambers and 2-chambers, respectively including maximum (V max), minimum (V min), and pre-atrial contraction (V pre-A), total atrial stroke volume (TA-SV), TA emptying fraction (TA-EF), active atrial SV (AA-SV), AA-EF, passive atrial SV (PA-SV), PA-EF, atrial expansion index (AEI), and LA kinetic energy (LA-KE) = (1/2) x AA-SV x P x V2. RESULTS: LAD, LA mass, V max, V min, and V pre-A were significantly higher in HCM than controls. TA-SV and TA-EF were comparable in both HCM subgroups and controls. AA-SV and LA-KE were significantly higher in both HCM subgroups than controls. LA-KE was significantly higher in obstructive HCM than non-obstructive (P < 0. 001). PA-EF and AEI were significantly lower in obstructive HCM than controls (P < 0. 05). CONCLUSION: HCM is associated with increased LA size and augmented LA pump function especially obstructive type. LA conduit and reservoir functions are impaired in obstructive HCM.

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