Submaximal exercise testing detected T wave alternans with an 84% concordance rate to atrial pacing, with comparable heart rate thresholds for onset (100 vs 97 beats/min, P=NS).
Observational (n=30)
Does submaximal exercise testing reliably detect microvolt T wave alternans compared to atrial pacing in patients with a history of ventricular tachyarrhythmias?
Microvolt T wave alternans can be reliably and noninvasively assessed during exercise stress, with heart rate being the main determinant of its onset.
Absolute Event Rate: 100% vs 97%
p-value: p=NS
INTRODUCTION: Evidence is accumulating that microvolt T wave alternans (TWA) is a marker of increased risk for ventricular tachyarrhythmias. Initially, atrial pacing was used to elevate heart rate and elicit TWA. More recently, a noninvasive approach has been developed that elevates heart rate using exercise. METHODS AND RESULTS: In 30 consecutive patients with a history of ventricular tachyarrhythmias, the spectral method was used to detect TWA during both atrial pacing and submaximal exercise testing. The concordance rate for the presence or absence of TWA using the two measurement methods was 84%. There was a patient-specific heart rate threshold for the detection of TWA that averaged 100 +/- 14 beats/min during exercise compared with 97 +/- 9 beats/min during right atrial pacing (P = NS). Beyond this threshold, there was a significant and comparable increase in level of TWA with decreasing pacing cycle length and increasing exercise heart rates. CONCLUSIONS: The present study is the first to demonstrate that microvolt TWA can be assessed reliably and noninvasively during exercise stress. There is a patient-specific heart rate threshold beyond which TWA continues to increase with increasing heart rates. Heart rate thresholds for the onset of TWA measured during atrial pacing and exercise stress were comparable, indicating that heart rate alone appears to be the main factor of determining the onset of TWA during submaximal exercise stress.
Hohnloser et al. (Mon,) conducted a observational in History of ventricular tachyarrhythmias (n=30). Submaximal exercise testing vs. Right atrial pacing was evaluated on Patient-specific heart rate threshold for the detection of TWA (beats/min) (p=NS). Submaximal exercise testing detected T wave alternans with an 84% concordance rate to atrial pacing, with comparable heart rate thresholds for onset (100 vs 97 beats/min, P=NS).