RT-106
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Late potentials and mitral valve
prolapse: incidence and clinical implications
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Emanuele Palumbo, Alberto Cresti,
Nedo Svetoni, Gennaro Miracapillo, Elena Mazzella, Teodomiro Lanzetta.
Divisione di Cardiologia, Ospedale della Misericordia, Azienda USL 9, Grosseto,
Italy
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Abstract
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Background. Mitral valvular prolapse
is a common and mostly benign valvular disease, but a subset of these patients is at risk
of sudden death that sometimes is the first manifestation of the disease. Late potentials
were considered by some authors non invasive markers of electrical instability in mitral
valve prolapse.
Methods. To assess the incidence and clinical implications of late
potentials in patients with mitral valve prolapse (MVP), we performed SAECG with high band
frequency of 25 and 40 Hz and 24-hour Holter monitoring in 31 patients with moderate to
severe mitral valve prolapse diagnosed by M-mode and twodimensional echocardiograms.
Twenty-two patients had thin valvular leaflets (Group I), while 9 patients had
"floppy" ones, thickened and redundant as in the myxomatous degeneration (Group
II).
Results. All patients of Group I had a moderate MVP, 3 subjects of
Group II had a severe one. At the color flow no patient in Group I had a significant
mitral regurgitation, while it was present in 3 subjects of Group II. No patient of both
groups showed episodes of sustained or non-sustained ventricular tachycardia. No patient
of Group I showed late potentials, while 5 subjects of Group II (55.5%) had an abnormal
SAECG and all five had myxomatous mitral valve. None of these five had more than Lown's
third grade ventricular arrhythmias at the Holter monitoring. In a mean follow-up of 31
months there were no deaths.
Conclusions. Evidences from our study seem to show that the incidence
of late potentials in MVP is significantly higher than in healthy subjects (16.1% vs 3.8%;
p < 0.05) and that their presence is correlated to the myxomatous degeneration of
mitral valve. This positivity of SAECG could depend on a potentially arrhythmogenic
myocardial substrate represented by a focal cardiomyopathy of the right ventricle,
recently confirmed by histological studies of other authors. If additional studies will
proved these data, late potentials could represent a non invasive marker of this abnormal
myocardial substrate and identify a subset of patients with MVP at risk of sudden death,
that is sometimes the first manifestation of the disease.
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Key Words
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Signal averaged ECG
late potentials, mitral valve prolapse, myxomatous degeneration of mitral valve, risk of
sudden death, OA
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