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. 2009 Feb;30(3):330-7.
doi: 10.1093/eurheartj/ehn466. Epub 2008 Oct 21.

Left ventricular mechanical dispersion by tissue Doppler imaging: a novel approach for identifying high-risk individuals with long QT syndrome

Kristina Hermann Haugaa  1 , Thor Edvardsen, Trond P Leren, Jon Michael Gran, Otto A Smiseth, Jan P Amlie
Affiliations

Left ventricular mechanical dispersion by tissue Doppler imaging: a novel approach for identifying high-risk individuals with long QT syndrome

Kristina Hermann Haugaa et al. Eur Heart J. 2009 Feb.

Abstract

Aims: The aim of this study was to investigate whether prolonged and dispersed myocardial contraction duration assessed by tissue Doppler imaging (TDI) may serve as risk markers for cardiac events (documented arrhythmia, syncope, and cardiac arrest) in patients with long QT syndrome (LQTS).

Methods and results: Seventy-three patients with genetically confirmed LQTS (nine double- and 33 single-mutation carriers with previous cardiac events and 31 single-mutation carriers without events) were studied. Myocardial contraction duration was prolonged in each group of LQTS patients compared with 20 healthy controls (P < 0.001). Contraction duration was longer in single-mutation carriers with previous cardiac events compared with those without (0.46 +/- 0.06 vs. 0.40 +/- 0.06 s, P = 0.001). Prolonged contraction duration could better identify cardiac events compared with corrected QT (QTc) interval in single-mutation carriers [area under curve by receiver-operating characteristic analysis 0.77 [95% confidence interval (95% CI) 0.65-0.89] vs. 0.66 (95% CI 0.52-0.79)]. Dispersion of contraction was more pronounced in single-mutation carriers with cardiac events compared with those without (0.048 +/- 0.018 vs. 0.031 +/- 0.019 s, P = 0.001).

Conclusion: Dispersion of myocardial contraction assessed by TDI was increased in LQTS patients. Prolonged contraction duration was superior to QTc for risk assessment. These new methods can easily be implemented in clinical routine and may improve clinical management of LQTS patients.

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Figures

Figure 1
Figure 1
Algorithm of study participants. The groups of healthy individuals and individuals on beta-blocker therapy represent the control groups.
Figure 2
Figure 2
Myocardial contraction duration by tissue Doppler imaging. Myocardial velocities (upper panels) and strains (lower panels) from a healthy individual (left) and a long QT syndrome patient (right).
Figure 3
Figure 3
Myocardial mechanical dispersion by tissue Doppler imaging. The left panels show velocity curves from four different segments in a healthy individual in four-chamber (upper left) and apical long-axis views (lower left). The right panels show velocity curves from a symptomatic long QT syndrome patient. White markers show the shortest and the longest contraction durations in each person. The difference in contraction duration is 0.03 s in the healthy individual and 0.12 s in the long QT syndrome patient and is consistent with the mechanical dispersion of contraction.
Figure 4
Figure 4
Receiver-operating characteristic curves of cardiac events (documented arrhythmia, syncope, or aborted cardiac arrest) in 64 single long QT syndrome mutation carriers (33 symptomatic and 31 asymptomatic). Myocardial contraction duration shows higher sensitivity and specificity for cardiac events compared with corrected QT interval. Area under curve 0.77 (95% CI 0.65–0.89) vs. 0.66 (95% CI 0.52–0.79).
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