Key result
Presence of fQRS in ≥3 territories and QTc ≥460 ms were independently associated with ventricular tachyarrhythmias or sudden cardiac death in HCM.
Why the study?
Does the presence of QRS fragmentation or prolonged QTc duration predict ventricular tachyarrhythmias and sudden cardiac death in patients with hypertrophic cardiomyopathy?
Cohort (n=195)
Does the presence of QRS fragmentation or prolonged QTc duration predict ventricular tachyarrhythmias and sudden cardiac death in patients with hypertrophic cardiomyopathy?
Answers are grounded in this paper and cite their sources.
QRS fragmentation in ≥3 territories and QTc ≥460 ms provide incremental predictive value for malignant ventricular arrhythmias and sudden cardiac death in HCM patients beyond conventional risk factors.
BACKGROUND: QRS fragmentation (fQRS) and prolonged QTc interval on surface ECG are prognostic in various cardiomyopathies other than hypertrophic cardiomyopathy (HCM). The association between fQRS and prolonged QTc duration with occurrence of ventricular tachyarrhythmias or sudden cardiac death (VTA/SCD) in patients with HCM was explored. METHODS AND RESULTS: One hundred and ninety-five clinical HCM patients were studied. QTc duration was derived applying Bazett's formula; fQRS was defined as presence of various RSR' patterns, R or S notching and/or >1 additional R wave in any non-aVR lead in patients without pacing or (in)complete bundle branch block. The endpoints comprised SCD, ECG documented sustained VTA (tachycardia or fibrillation) or appropriate implantable cardioverter defibrillator (ICD) therapies (antitachycardia pacing [ATP] or shock) for VTA in ICD recipients (n = 58 [30%]). QT prolonging drugs recipients were excluded. After a median follow-up of 5.7 years (IQR 2.7-9.1), 26 (13%) patients experienced VTA or SCD. Patients with fQRS in ≥3 territories (inferior, lateral, septal, and/or anterior) (p = 0.004) or QTc ≥460 ms (p = 0.009) had worse cumulative survival free of VTA/SCD than patients with fQRS in <3 territories or QTc <460 ms. fQRS in ≥3 territories (ß 4.5, p = 0.020, 95%CI 1.41-14.1) and QTc ≥460 ms (ß 2.7, p = 0.037, 95%CI 1.12-6.33) were independently associated with VTA/SCD. Likelihood ratio test indicated assessment of fQRS and QTc on top of conventional SCD risk factors provides incremental predictive value for VTA/SCD (p = 0.035). CONCLUSIONS: Both fQRS in ≥3 territories and QTc duration are associated with VTA/SCD in HCM patients, independently of and incremental to conventional SCD risk factors.
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Debonnaire et al. (2015) conducted a cohort in Hypertrophic Cardiomyopathy (n=195). QRS fragmentation (fQRS) in ≥3 territories and QTc ≥460 ms vs. fQRS in <3 territories or QTc <460 ms was evaluated on Sudden cardiac death (SCD), ECG documented sustained VTA, or appropriate ICD therapies (ß 4.5, 95% CI 1.41-14.1, p=0.020). Presence of fQRS in ≥3 territories and QTc ≥460 ms were independently associated with ventricular tachyarrhythmias or sudden cardiac death in HCM.
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