Imaging-Based Risk Stratification for Sudden Cardiac Death in Hypertrophic Cardiomyopathy: Current Evidence and Clinical Perspectives

Figures

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  Figure 1. Short-axis maximal MWT measurement by TTE (A) and CMR (B). In the TTE image, 1 and 2 indicate the interventricular septum and 3 and 4 indicate the posterior wall. In the CMR image, 1 indicates the interventricular septum and 2 indicates the posterior wall. CMR: Cardiac magnetic resonance; LV: Left ventricle; RV: Right ventricle; MWT: Myocardial wall thickness; TTE: Transthoracic echocardiography.

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  Figure 2. (A) LVOT dynamic gradient (85 mmHg, Vmax 4.62 m/s) measurement with the continuous doppler by TTE (number 1). (B) Presence of SAM of the mitral valve (arrow) assessed by TTE. Ao: Aorta; LA: Left atrium; LVOT: Left ventricle outflow tract; MV: Mitral valve; SAM: Systolic anterior movement; TTE: Transthoracic echocardiography; V: Velocity.

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  Figure 3. Apical aneurysm (arrow) in a 2−chamber view by TTE (A) and in 4−chamber (B) and 3−chamber (C) views by CMR. Ao: Aorta; CMR: Cardiac magnetic resonance; LA: Left atrium; LV: Left ventricle; TTE: Transthoracic echocardiography.

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  Figure 4. (A) LA anteroposterior diameter measurement by TTE. (B) Two−chamber and (C) 4−chamber LA volume measurement by TTE. (D) Two−chamber and (E) 4−chamber LA and RA volume measurement by CMR. The orange lines represent the LA perimeter, the pink lines represent the maximal LA diameter, the blue line represents the RA perimeter, and the yellow line represents the maximal RA diameter. Ao: Aorta; CMR: Cardiac magnetic resonance; LA: Left atrium; LV: Left ventricle; RA: Right atrium; RV: Right ventricle; TTE: Transthoracic echocardiography.

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  Figure 5. LA strain measurement by TTE and CRM. (A) Four−chamber and (B) 2−chamber TTE views and their respective R−wave deformation graphics. LA strain analysis is performed using ECG R−wave gating (onset of ventricular systole); with an initial upward deflection reflecting LA filling and stretching during LV systole, followed by a downward slope corresponding to LA emptying. The LA strain curve (white curves in Figure 5A,B and red curves in Figure 5C) comprises three functional phases: the reservoir phase (LASr), during which the LA fills from the pulmonary veins while the mitral valve remains closed; the conduit phase (LASc), in which mitral valve opens and blood passively flows into LV; and the booster phase (LASb), which reflects active atrial contraction. (C) Four-chamber CMR view with subsequent strain analysis graphic. The green line represents the perimeter of the LA and the blue line shows the Doppler index (dV/dt) which represents the rate of change in blood flow velocity over time, providing an index of flow acceleration and haemodynamic performance throughout the cardiac cycle. Positive deflections correspond to flow acceleration, whereas negative deflections reflect flow…

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  Figure 6. Prognostic impact of impaired LVEF regarding SCD. ACC/AHA: American College of Cardiology/American Heart Association; CMR: Cardiac magnetic resonance; ESC: European Society of Cardiology; HCM: Hypertrophic cardiomyopathy; HF: Heart failure; HR: Hazard ratio; ICD: Implantable cardioverter-defibrillator; LV: Left ventricle; LVEF: Left ventricular ejection fraction; SCD: Sudden cardiac death; TTE: Transthoracic echocardiography.

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  Figure 7. Prognostic impact of impaired diastolic function regarding sudden cardiac death. HCM: Hypertrophic cardiomyopathy; HF: Heart failure; LV: Left ventricle; RV: Right ventricle; SCD: Sudden cardiac death; TTE: Transthoracic echocardiography.

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  Figure 8. (A,B) LV longitudinal strain (−19.4%) measurement by TTE. (C) LV radial strain measurement using the CMR CVI42 software (Circle Cardiovascular Imaging Inc., Calgary, AB, Canada). Ao: Aorta; CMR: Cardiac magnetic resonance; FE: Fraction ejection; LA: Left atrium; LV: Left ventricle. SG: Strain global; TTE: Transthoracic echocardiography.

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  Figure 9. (A) LV longitudinal strain measurement in 2−chamber view and strain quantification using the CMR CVI42 software. The colours used in the CMR images are intended for illustrative purposes only and do not represent quantitative measurements, with the exception of the polar map, where the displayed scale accurately quantifies LV longitudinal strain values. (B) LV and (C) RV longitudinal strain measurements using the CMR MEDIS Suite MR software (MEDIS Medical Imaging Systems, Leiden, The Netherlands). The red lines represent the GLS measurements; the blue lines indicate the Doppler index (dV/dt); the pink line corresponds to GCS; and the green line to GRS. AHA: American Heart Association (17-segment model); CMR: Cardiac magnetic resonance; GCS: Global circumferential strain; GLS: Global longitudinal strain; GRS: Global radial strain; LA: Left atrium; LV: Left ventricle; RA: Right atrium; RV: Right ventricle.

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  Figure 10. Patchy LGE distribution (asterisks), predominantly localized to the most hypertrophied myocardial regions and the RV insertion points. (A) Two− and 4−chamber CMR views. (B,C) Short−axis CMR views. CMR: Cardiac magnetic resonance; LGE: Late gadolinium enhancement; LV: Left ventricle; RV: Right ventricle. CMR: Cardiac magnetic resonance; LA: Left atrium; LGE: Late gadolinium enhancement; LV: Left ventricle.

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  Figure 11. Potential prognostic impact of LGE regarding SCD. HCM: Hypertrophic cardiomyopathy; LGE: Late gadolinium enhancement; SCD: Sudden cardiac death.

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  Figure 12. (A) T2 mapping sequences in 4−chamber and short−axis CMR views. The white circles indicate regions of interest with elevated T2 values. (B) Noncontrast native T1 mapping in 4−chamber and short−axis CMR views. The white circle indicates a region of interest with elevated T1 values (1120 ms), and the red circle indicates a region with normal T1 values (980 ms). CMR: Cardiac magnetic resonance; LA: Left atrium; LV: Left ventricle; RA: Right atrium; RV: Right ventricle.