Tissue Doppler-Derived Left Ventricular Systolic Velocity Is Associated with Lethal Arrhythmias in Cardiac Device
Mohamad F Barakat1, Omar Chehab2, Amit Kaura3
1School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, James Black Centre, London, United Kingdom; Department of Cardiology, King's College Hospital, London, United Kingdom.
Insights
Mitral annular systolic velocity (S') predicts life-threatening arrhythmias (LTAs) in cardiac device recipients. Higher S' values indicate a lower risk of LTAs, irrespective of left ventricular ejection fraction (LVEF).
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Imaging
Background:
- Life-threatening arrhythmias (LTAs) increase mortality and morbidity, often necessitating implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) implantation.
- The subendocardium, rich in longitudinal myofibrils, is particularly susceptible to arrhythmogenic triggers.
- Left ventricular ejection fraction (LVEF) is a known factor in arrhythmia risk, but its predictive capacity for LTAs may be limited.
Purpose of the Study:
- To investigate whether mitral annular systolic velocity (S"), a tissue Doppler index of left ventricular (LV) long-axis function, can predict LTAs.
- To determine if S' provides predictive value for LTAs independently of LVEF.
- To explore the potential clinical utility of S' in managing patients at risk for arrhythmias.
Main Methods:
- Retrospective analysis of 302 patients who received an ICD or CRT-D.
- Mitral annular systolic velocity (S") was averaged from tissue Doppler-derived medial and lateral mitral annular velocities.
- Correlation of S' with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) requiring device therapy, analyzed using Cox regression.
Main Results:
- A higher S' was significantly associated with a decreased risk of LTAs (HR=0.70 per 1 cm/sec increase, P=0.001).
- This association remained independent of LVEF and other clinical factors.
- An S' cutoff > 5.6 cm/sec identified patients with a 58% lower risk of LTAs compared to those with S' ≤ 5.6 cm/sec (P=0.02).
Conclusions:
- Increased mitral annular systolic velocity (S") is linked to a reduced likelihood of life-threatening arrhythmias in patients with cardiac devices.
- S' may serve as a valuable clinical marker for stratifying arrhythmic risk beyond LVEF.
- S' could potentially guide therapeutic decisions for medical, device, and ablative interventions to mitigate future arrhythmic events.
Background:
Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S'), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF).
Methods:
This is a retrospective analysis of data from 302 patients (mean age, 68 years; LVEF, 32%; 77% male; 52% ischemic; 35% primary prevention; and 53% cardiac resynchronization therapy defibrillator [CRT-D]) who were followed up (median, 15 months) at two centers after receipt of an ICD or CRT-D for diverse indications. S', averaged from tissue Doppler-derived medial and lateral mitral annular velocities, was correlated with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy.
Results:
The median S' was 5.1 (interquartile range, 4.0-6.2) cm/sec and lower in CRT-D than ICD subjects (4.5 [3.8-5.6] cm/sec vs 5.5 [4.8-6.8] cm/sec, P < .001). Fifty-six (19%) subjects had LTA. Each 1 cm/sec higher S' correlated to a 30% decreased risk of LTA (hazard ratio = 0.70; 95% CI, 0.57-0.87; P = .001) independently of age, sex, β-blocker use, center, ICD use, and LVEF. Adding S' to the baseline Cox model improved net reclassification (P = .02). An S' > 5.6 cm/sec was the best cutoff and linked to a 58% lower LTA risk than an S' ≤ 5.6 cm/sec (95% CI, 0.23-0.85; P = .02).
Conclusions:
A higher S' is associated with a reduced probability of LTA in cardiac device recipients irrespective of LVEF and may have the potential to be used clinically to titrate medical, device, and ablative therapies to mitigate future arrhythmic risk.
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