Fragmented QRS complex has poor sensitivity in detecting myocardial scar.

OBJECTIVE

To study the association of the fragmented QRS complex versus the Q wave with myocardial scar and viability.

BACKGROUND

A prior study has suggested that the fragmented QRS complex on an electrocardiogram (ECG) is a highly sensitive and specific marker of myocardial scar as detected by regional perfusion abnormalities on a nuclear stress test. There is no external validation of this data.

METHODS

We correlated the ECG and nuclear perfusion images of 460 consecutive patients with known or suspected coronary artery disease. The presence of fragmented QRS or Q waves in two contiguous ECG leads was correlated with major coronary artery distributions on nuclear perfusion imaging.

RESULTS

For the 1842 evaluated territories, the fragmented QRS complex was not superior to the Q wave in detecting fixed or mixed myocardial defects. The fragmented QRS complex was associated with worse sensitivity (1.7%) in comparison to the Q wave (31.7%) for identifying myocardial scar. The fragmented QRS complex carried a higher false positive rate in patients with normal perfusion scans (15.8%, 221 segments), in comparison to Q waves (1.4%, 17 segments).

CONCLUSION

In our study population, both the fragmented QRS and Q wave had poor sensitivity and specificity in detecting fixed or mixed myocardial scar. Larger studies are needed to evaluate fragmented QRS as a surrogate of myocardial scar before it can be incorporated into clinical practice.