Mark E. Alexander
MD, Frank Cecchin MD, Kathie P. Huang BS, Laura M. Bevilacqua MD, John K.
Triedman MD, Edward P. Walsh MD, Charles I. Berul MD, Children's Hospital
Boston, Boston, MA.
Background: Microvolt t-wave alternans (TWA) in early exercise is a non-invasive
marker of life threatening ventricular arrhythmia in some adult cardiac
populations. The incidence and potential significance sustained TWA in
pediatric and congenital heart disease (CHD) populations has not been well
defined. Methods: TWA treadmill exercise studies in pediatric pts with CHD,
myopathy, potential myocardial ischemia, syncope or history of cardiac arrest
were analyzed. Tests were categorized as abnormal for sustained TWA with onset
heart rate < 130 bpm and physiologic TWA for onset HR>130. Pt
characteristics were analyzed as possible correlates of TWA. Results: Over 2
years 319 consecutive TWA exercise studies were performed in 303 pts (60% male,
median 14 yrs, 6-41) for indications of syncope, cardiac arrest, possible
ventricular arrhythmia or evaluation of functional myocardial perfusion. Underlying
conditions included apparently normal hearts (45%), CHD (16%), cardiomyopathy
(11%), coronary anomalies (11%) and electrical myopathy (9%) and
transplant(8%). Abnormal TWA was seen in 24 (7%, onset HR 106±18) and included 19 at high clinical risk for serious
events including 3 with cardiac arrest (table). Abnormal TWA was associated
with identified functional myocardial abnormalities, and less likely in pts
with no identified arrhythmia and benign syncope. The predictive strength
increased when corrected for other clinical risk factors. Conclusions: TWA with
onset HR< 130 is associated with pediatric and CHD diagnoses at high risk of
serious events and may contribute, with other diagnostic tools, to management
choices. The absence of TWA does not exclude the potential for serious
sustained ventricular arrhythmias.
|
TWA |
High
Risk |
Low
Risk |
|
Abnormal |
19 |
5 |
|
Normal |
64 |
215 |
|
Odds ratio 12.7, 4.5-35, p<.001, abnormal TWA
predicting high risk pt, sensitivity 23%, specificity 98%, PPV 79%, NPV 77% |
||