Key result
High arrhythmia score linked to ~103% greater short-term QT-interval variability compared to low scores.
Why the study?
Does the circadian pattern of short-term variability of the QT-interval differ between primary prevention ICD patients with high versus low arrhythmia risk?
Observational (n=30)
Does the circadian pattern of short-term variability of the QT-interval differ between primary prevention ICD patients with high versus low arrhythmia risk?
In primary prevention ICD patients, short-term variability of the QT-interval peaks in the early morning and late afternoon among those with high arrhythmia risk, suggesting these times may be optimal for prospective risk assessment.
Answers are grounded in this paper and cite their sources.
Higher morning STV-QT may mark elevated arrhythmia risk in primary prevention ICD patients; this observational link leaves open prospective validation for risk stratification.
OBJECTIVE: Short-term variability of the QT-interval (STV-QT) was shown to be associated with an increased risk of ventricular arrhythmias. We aimed at investigating (a) whether STV-QT exhibits circadian pattern, and (b) whether such pattern differs between patients with high and low arrhythmia risk. METHODS: As part of the ongoing EU-CERT-ICD study, 24h high resolution digital ambulatory 12-lead Holter recordings are collected prior to ICD implantation for primary prophylactic indication. Presently available patients were categorized based on their arrhythmia score (AS), a custom-made weighted score of the number of arrhythmic events on the recording. STV-QT was calculated every hour in 30 patients of which 15 and 15 patients had a high and a low AS, respectively. RESULTS: The overall dynamicity of STV-QT showed high intra- and inter-individual variability with different circadian patterns associated with low and high AS. High AS patients showed a prominent peak both at 08:00 and 18:00. At these times, STV-QT was significantly higher in the high AS patients compared to the low AS patients (1.22ms±0.55ms vs 0.60ms±0.24ms at 08:00 and 1.12ms±0.39ms vs 0.64ms±0.29ms at 18:00, both p < 0.01). CONCLUSION: In patients with high AS, STV-QT peaks in the early morning and late afternoon. This potentially reflects increased arrhythmia risk at these times. Prospective STV-QT determination at these times might thus be more sensitive to identify patients at high risk of ventricular arrhythmias.
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Sprenkeler et al. (2017) conducted an observational in Primary prevention ICD patients (n=30). High arrhythmia score vs. Low arrhythmia score was evaluated on Short-term variability of the QT-interval (STV-QT) at 08:00 (p=< 0.01). Patients with a high arrhythmia score exhibited significantly higher short-term variability of the QT-interval at 08:00 compared to low-score patients (1.22 vs 0.60 ms; p<0.01).
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