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Published on: May 24, 2021
Left ventricular geometry predicts ventricular tachyarrhythmia in patients with left ventricular systolic
Shiro Nakamori1, Haisam Ismail1, Long H Ngo1
1Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA.
Insights
Left ventricular (LV) sphericity index, measured by cardiovascular magnetic resonance (CMR), predicts ventricular arrhythmias in patients receiving an implantable cardioverter-defibrillator (ICD). Higher sphericity indicates increased risk for appropriate ICD therapy.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Many patients with implantable cardioverter-defibrillators (ICDs) do not utilize their devices, leading to increased healthcare costs and potential patient harm.
- Predicting which patients will benefit from ICDs is crucial for optimizing their use in primary prevention of sudden cardiac death.
Purpose of the Study:
- To investigate whether left ventricular (LV) spherical remodeling, assessed by volumetric cardiovascular magnetic resonance (CMR), can predict future ventricular arrhythmias in primary ICD patients with reduced LV ejection fraction (EF).
Main Methods:
- Sixty-eight patients with LV ejection fraction (LVEF) <35% underwent CMR before ICD implantation.
- LV sphericity index was calculated as the ratio of LV end-diastolic volume to the volume of a sphere based on LV end-diastolic length.
- Multivariable Cox's proportional hazard modeling was used to identify predictors of appropriate ICD therapy.
Main Results:
- Over a median follow-up of 55 months, 22% of patients received appropriate ICD therapy.
- An increased CMR-derived sphericity index was the strongest independent predictor of appropriate ICD therapy (HR, 1.09; P=.007).
- A sphericity index ≥0.57 indicated a 4-fold increased hazard risk for appropriate ICD therapy, independent of age and LVEF.
Conclusions:
- Volumetric CMR-derived LV sphericity index is a significant predictor of ventricular arrhythmias requiring appropriate ICD therapy in primary prevention patients.
- Combining LV sphericity index, LVEF, and mass index provides incremental prognostic information for these patients.
- This approach may help refine patient selection for ICD implantation, improving device utilization and patient outcomes.
Background:
Most patients with implantable cardioverter-defibrillator (ICD) implantation fail to utilize the device resulting in increasing societal costs and patient exposure to device morbidity. We sought to determine whether volumetric cardiovascular magnetic resonance (CMR) left ventricular (LV) spherical remodeling predicts future ventricular arrhythmias in primary ICD patients with reduced LV ejection fraction (EF).
Methods:
Sixty-eight consecutive patients with transthoracic echocardiographic LVEF <35% referred for CMR prior to ICD implantation for primary prevention of sudden death were identified. Sphericity index was measured as the ratio of LV end-diastolic volume (from cine short axis stack) to the volume of a sphere with a LV end-diastolic 4-chamber length diameter.
Results:
During a median follow-up of 55 months (interquartile range; 28-88), 15 patients (22%) received appropriate ICD therapy. Multivariable Cox's proportional hazard modeling identified increased CMR-derived sphericity index as the strongest independent predictor of appropriate ICD therapy (hazard ratio [HR], 1.09; 95% confidence interval [CI], 1.02 to 1.16; p = 0.007). In addition, dichotomized volumetric CMR-derived sphericity index ≥0.57 carried a 4-fold hazard risk for appropriate ICD therapy, controlling for age and LVEF (HR, 4.49; 95% CI, 1.53 to 13.21; p = 0.006). When sphericity index, LVEF and mass index were used in combination, important incremental prognostic information was achieved (net reclassification improvement, 0.42; 95% CI, 0.06 to 0.77).
Conclusions:
The combined assessment of LV geometry, mass index and systolic function may provide incremental prognostic information regarding ventricular arrhythmia requiring appropriate ICD therapy in primary prevention patients with reduced LVEF.
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