Extracted from European Heart Journal (2007) 28, 2303-2304

“In the present study, TWA was determined

as an absolute value with a new time domainmodified

moving average method. The authors tested

multiple cut-off points and found that at 65 mV the best

statistical values were obtained. However, since there is

no gold standard, additional studies are needed in other

specific populations to determine which amount of TWA provides

the best diagnostic and prognostic information. The

sensitivity and positive predictive value of TWA were fairly

low (,35 and ,15%), requiring additional diagnostic tests

to establish cardiovascular risk. In the present study, the

results and predictive value of exercise testing were not

provided, thus the additional value of the TWA test

remains unknown.

Another important issue concerns the mechanism of TWA

in this low risk, general population. TWA may be observed

in patients with a history of MI as a strong predictor for

cardiac death, even if LV function is preserved.3,4 In the

study by Nieminen et al., about 90% had a normal LVEF on

echocardiography, although data were only obtained in

half of the patients. Up to 30% had a history of coronary

heart disease including MI, and 40–50% had important comorbidity

such as hypertension and diabetes mellitus, but

these did not surface as significant risk factors. One

wonders what the basis for the positive TWA test might be

then in a patient without any apparent cardiac abnormality.

There is no information on how these patients were treated

during follow-up on the basis of either exercise test or TWA

test, and whether this affected the natural outcome. Moreover,

how should one treat a person with a positive TWA test

in the absence of an identifiable substrate? The mortality

end-points of the study were taken from public records,

which may raise concern over definitions and reliability.

How the TWA test related to specific causes of death in

this population, such as acute coronary syndrome, acute

heart failure, or ventricular arrhythmias, remains unclear.”