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November 1, 2008Hypertension ResearchOpen Access

Prolonged QT Interval and Reduced Heart Rate Variability in Patients with Uncomplicated Essential Hypertension

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Why the study?

Is a prolonged QT interval associated with reduced heart rate variability in patients with untreated uncomplicated essential hypertension?

Population

215 untreated patients with uncomplicated essential hypertension

Comparison

Prolonged QTc (≥440 ms) vs Normal QTc (<440 ms)

Design

Cross-sectional

Key result

In patients with untreated essential hypertension, a prolonged QTc interval was associated with significantly reduced heart rate variability, including a lower 24-hour SDNN (126.4 vs 143.9 ms).

Authors

SMSimona MauleFRFranco RabbiaVPValentina Perni

Discussion

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Overview

May indicate autonomic dysfunction in untreated hypertension; hypothesis-generating and requires prospective validation before clinical use.

Study Design

Type

Cross-Sectional (n=215)

Multicenter

No

Structured PICO

Is a prolonged QT interval associated with reduced heart rate variability in patients with untreated uncomplicated essential hypertension?

P
Population
215 untreated patients with uncomplicated essential hypertension
I
Intervention
Prolonged QTc (≥440 ms)
C
Comparator
Normal QTc (<440 ms)
O
Outcome
Heart rate variability (HRV) indexes in the time domain (SDNN, SDNN index, RMSSD, and pNN50)surrogate

Main Result

Absolute Event Rate: 126.4% vs 143.9%

p-value: p=0.02

In untreated essential hypertension, a prolonged QTc interval is associated with reduced heart rate variability, suggesting coexisting autonomic dysfunction and increased cardiovascular risk.

Limitations

  • Single examination does not allow consideration of spontaneous variability of QT interval over time
  • Semi-automatic analysis of the 24 h Holter ECG may be affected by artefacts and sinus arrhythmia
  • Correction of QT length by means of the controversial Bazett's formula
  • Predominance of females in the prolonged QTc group
  • Lack of a normotensive control group

Cite This Study

Maule et al. (2008) conducted a cross-sectional in Untreated uncomplicated essential hypertension (n=215). Prolonged QTc (≥440 ms) vs. Normal QTc (<440 ms) was evaluated on 24-hour SDNN (Standard deviation of all normal-to-normal intervals) (p=0.02). In patients with untreated essential hypertension, a prolonged QTc interval was associated with significantly reduced heart rate variability, including a lower 24-hour SDNN (126.4 vs 143.9 ms).

synapsesocial.com/papers/6a125f75bb918b6e5b673239https://doi.org/10.1291/hypres.31.2003
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