Abstract
Introduction: Fragmented QRS (fQRS) in 12-lead electrocardiography is reported to be a predictor of cardiac prognosis in ischemic heart disease. In contrast, certain studies have reported that fQRS is associated with cardiac resynchronization therapy response. However, few studies have evaluated the diagnostic performance of local fQRS using semiconductor single photon emission computed tomography (SPECT). Hypothesis: fQRS is a powerful indicator of anterior myocardial ischemia and left ventricular (LV) dyssynchrony. Methods: A total of 740 consecutive sinus rhythm patients with various cardiac diseases underwent SPECT with adenosine stress. The local fQRS was classified into I/aVL/V5-6 (lateral), II/III/aVF (inferior), and V1-4 (anterior). Cases with wide QRS (>120ms), obvious right bundle branch block, and where fQRS existed in multi-classes were excluded. A 17-segment model of myocardial perfusion SPECT was divided into 3 areas: anterior, inferior, and lateral. Each summed score at rest (SRS), under stress (SSS), and the difference (SDS) was calculated. Results: fQRS was present in 82 cases (lateral, 13; anterior, 15; inferior, 54) and analysis of variance showed that anterior SSS was significantly higher in anterior fQRS cases (p=0.012). Histogram bandwidth of LV contraction onset - a known dyssynchrony parameter - was significantly higher in lateral fQRS cases (p135 degrees and SD>43 degree, lateral fQRS had a high OR (7.91) with significant 95%CI (2.32-27.0) for indicating the condition. Conclusions: fQRS in anterior leads is a significant indicator of anterior wall ischemia; and fQRS in lateral leads is a significant indicator of LV dyssynchrony.
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