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Left Ventricular Longitudinal Function Predicts Life-Threatening Ventricular Arrhythmia and Death in Adults With Repaired Tetralogy of Fallot
Study Questions:
What is the impact of left ventricular (LV) longitudinal function on life-threatening ventricular arrhythmia and death in adults with repaired tetralogy of Fallot?
Methods:
A retrospective study was performed at two adult congenital heart centers. A composite endpoint of sudden cardiac death and life-threatening ventricular arrhythmia was used. Life-threatening arrhythmia was defined as sustained ventricular tachycardia, resuscitated sudden cardiac death, or appropriate implantable cardioverter-defibrillator (ICD) discharge. Peak global longitudinal 2D LV strain (LV-LS) was measured offline using a commercially available software package.
Results:
A total of 413 patients with tetralogy of Fallot (mean age 36 ± 13 years) were studied over a median follow-up period of 2.9 years (interquartile range, 1.4-4.4 years). The mean QRS duration at baseline was 148 ± 27 ms. Over the course of the follow-up period, five patients died suddenly, nine had documented sustained ventricular tachycardia, and an additional five patients had appropriate ICD discharges. On univariate Cox analysis, QRS duration (hazard ratio [HR], 1.02 per ms; p = 0.046), right atrial area (hazard ratio [HR], 1.05 per 1 cm2), right ventricular (RV) fractional area change (HR, 0.94 per 1%; p = 0.02), RV outflow tract diameter (HR, 1.08 per 1 mm; p = 0.01), mitral annular plane systolic excursion (HR, 0.84 per 1 mm; p = 0.03), and LV global longitudinal 2D strain (HR, 0.87 per 1%; p = 0.03). On bivariable analysis, mitral annular plane systolic excursion and LV-LS were related to outcome independently of QRS duration (p = 0.002 and 0.01, respectively). A combination of echocardiographic variables, including right atrial area, RV fractional area change, and LV-LS or mitral annular plane systolic excursion, was also found to be significantly related to outcome.
Conclusions:
The authors concluded that LV longitudinal dysfunction was associated with a greater risk of sudden cardiac death and life-threatening ventricular arrhythmias. LV-LS may be used in conjunction with other echocardiographic measures as well as the QRS duration in risk-stratifying adults with tetralogy of Fallot.
Perspective:
The annual risk of sudden cardiac death or life-threatening ventricular arrhythmia was 2.4% in this study, which is comparable to a previous report estimating the risk to be 2.9% (Harrild et al., Circulation 2009). A noninvasive and straightforward risk assessment tool would be extremely helpful in identifying candidates for therapies (specifically ICD) to diminish the risk of sudden cardiac death in this patient population. Other previously identified risk factors, including LV end-diastolic pressure, are not practical, as they require an invasive procedure. This study suggests that LV longitudinal function may become an important adjunct in risk assessment, although the development of a powerful risk score would require a large patient population with a relatively long follow-up period.
Keywords: Tetralogy of Fallot, Heart Atria, Follow-Up Studies, Heart Defects, Congenital, Ventricular Function, Left, Heart Conduction System, Blood Pressure, Risk Factors, Systole, Tachycardia, Ventricular, Risk Assessment, Defibrillators, Implantable, Death, Sudden, Cardiac, Echocardiography
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