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Lowering the Recommended Maximal Wall Thickness Threshold Improves Diagnostic Sensitivity in Asians With Hypertrophic
Thu-Thao Le1,2, Benjamin Huang1, Chee Jian Pua1,3
1Department of Cardiology, National Heart Centre Singapore, Singapore.
Insights
The standard diagnostic threshold for hypertrophic cardiomyopathy (HCM) may misdiagnose Asian individuals. Adjusting the maximal wall thickness (WTMax) criteria for ethnicity and sex improves HCM detection sensitivity in Asians without reducing specificity.
Area of Science:
- Cardiology
- Genetics
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) diagnosis relies on a maximal wall thickness (WTMax) threshold of ≥15.0 mm.
- This absolute threshold does not account for ethnic variations in heart size, such as smaller hearts in Asians compared to Caucasians.
Purpose of the Study:
- To evaluate the impact of the current absolute WTMax threshold on diagnosing HCM in the Asian population.
- To determine if adjusting WTMax criteria for ethnicity and sex can improve diagnostic accuracy.
Main Methods:
- Cardiovascular magnetic resonance imaging was performed on 360 healthy Asian volunteers and 114 genetically characterized HCM patients.
- Maximal wall thickness (WTMax) was measured semiautomatically at end-diastole.
- Diagnostic performance was assessed using the standard 15.0 mm threshold and adjusted thresholds.
Main Results:
- The standard 15.0 mm WTMax threshold showed 100% specificity but only 51% sensitivity for HCM in Asians.
- Adjusting thresholds to 10.0 mm for females and 12.0 mm for males significantly improved sensitivity to 84% while maintaining 100% specificity.
- Female HCM patients exhibited more adverse cardiac remodeling, including fibrosis and worse strain, despite smaller left ventricular mass.
Conclusions:
- The study recommends cautious application of the current guideline-recommended WTMax threshold for diagnosing HCM in Asians.
- Lowering WTMax thresholds based on ethnicity and sex enhances diagnostic sensitivity for HCM in Asians without compromising specificity.
- Sex-based differences in cardiac remodeling are evident in HCM patients.
Background:
Hypertrophic cardiomyopathy (HCM) is defined as left ventricular end-diastolic maximal wall thickness (WTMax) ≥15.0 mm, without accounting for ethnicity, sex, and body size. It is well-established that Asians have smaller hearts than do Caucasians.
Objectives:
This study aims to examine the implications of this single absolute WTMax threshold on the diagnosis of HCM in Asians.
Methods:
The study consisted of 360 healthy volunteers (male: n = 174; age: 50 ± 12 years) and 114 genetically characterized patients with HCM (male: n = 83; age: 52 ± 13 years; genotype-positive, n = 39). All participants underwent cardiovascular magnetic resonance. WTMax was measured semiautomatically at end-diastole according to the standard 16 myocardial segments.
Results:
Healthy male volunteers had increased WTMax compared with that of female volunteers (8.4 ± 1.2 mm vs 6.6 ± 1.1 mm, respectively; P < 0.001). Conversely, WTMax was similar between male and female patients with HCM (15.2 ± 3.4 mm vs 14.7 ± 3.0 mm, respectively; P = 0.484) and between those with and without a pathogenic gene variant (P = 0.828). Using the recommended diagnostic threshold of 15.0 mm, 56 patients with HCM had WTMax <15.0 mm and no healthy volunteers had WTMax >15.0 mm (specificity of 100% and sensitivity of 51%). Lowering WTMax thresholds to 10.0 mm in female patients and 12.0 mm in male patients did not affect specificity (100%) but significantly improved sensitivity (84%). Despite lower left ventricular mass, female patients with HCM demonstrated more features of adverse cardiac remodeling than did male patients: increased myocardial fibrosis, higher asymmetric ratio, and disproportionately worse myocardial strain.
Conclusions:
The study highlights cautious application of guideline-recommended WTMax to diagnose HCM in Asians. Lowering WTMax to account for ethnicity and sex improves diagnostic sensitivity without compromising specificity.
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