|
Presentation
Start/End Time:
|
Monday,
Mar 07, 2005, 3:30 PM - 4:30 PM
|
|
Author
Block:
|
Omer
Goktekin, Sonya V
Babu-Narayan, Philip J. Kilner, Richard Sutton, Michael A. Gaztzoulis, Royal
Brompton Hospital, London, United Kingdom, Osmangazi University, Eskisehir,
United Kingdom
|
|
Background:
Microvolt T wave alternans (TWA) is a new non-invasive method which has been
shown to identify patients at increased risk of cardiac arrest and sudden
cardiac death from ventricular arrhythmias in ischemic heart disease and
cardiomyopathies. Arrhythmia and sudden death are a significant cause of
morbidity and mortality late after atrial redirection surgery (Mustard or
Senning) for transposition of the great arteries. Post-operatively such
patients have a right ventricle sustaining systemic pressure over a lifetime
and are therefore at risk of late ventricular dysfunction. We hypothesised
that TWA would be present and sought to examine the relationship between TWA
and systemic right ventricular fibrosis.
Method: Seventeen patients (11 male, mean follow-up from atrial
redirection surgery of 26.5±12.4 years) were studied so far. All patients had
contrast enhanced cardiovascular magnetic resonance imaging. Nine patients
with right ventricular (RV) myocardial fibrosis suggested by delayed
enhancement magnetic resonance and 8 patients without fibrosis had TWA
testing. TWA was measured during submaximal treadmill exercise by the CH2000
system (Cambridge Heart, Inc) in all patients. Positive TWA was defined as an
alternans voltage amplitude ≥1.9 µV during exercise at a heart rate of
105-120 beats per minute with an alternans ratio (signal-to-noise ratio)
≥3 for at least 1 minute.
Results: TWA was positive in 5 patients (29%), negative in 10 patients
(58%) and indeterminate in 2 (11%). There was a trend towards decreased RV
ejection fraction and increased RV mass in the 5 patients with TWA (44 ± 23
vs 62 ± 5%, NS, 119 ± 53 vs 81 ± 18, NS). All positive TWA tests were in the
RV fibrosis group (5/9 vs 0/8, p<0.05). Patients with RV myocardial fibrosis
were older than those without (32 vs 23, p<0.01).
Conclusion: TWA was relatively common and related to RV myocardial
fibrosis seen in adult patients late after the Mustard operation. This may
suggest that myocardial fibrosis plays a role in the etiology of sudden
cardiac death in this group of patients and warrants further investigation.
|