[Factors Associated with the Increase in Spatial and Frontal QRS-T Angles in Patients with Inferior Myocardial...

Aim      To identify clinical, echocardiographic, and angiographic factors related with an increase in the frontal QRS-T angle (fQRS-T) and the spatial QRS-T angle (sQRS-T) in patients with inferior myocardial infarction.Material and methods  The study included 128 patients aged (median [25th percentile; 75th percentile]) 59.5 [51.5; 67.0] years diagnosed with inferior wall acute myocardial infarction. fQRS-T was calculated as a module of difference between the QRS axis and the Т axis in the frontal plane. sQRS-T was calculated by a synthesized vectorcardiogram as a spatial angle between the QRS and Т integral vectors.Results The fQRS-T for the group was 54.0 [18; 80] and sQRS-T was 80.1 [53; 110]. The correlation coefficient for fQRS-T and sQRS-T values was 0.42 (p<0.001). Both fQRS-T >80° and sQRS-T >110° compared to their lower values were associated with a higher frequency of history of postinfarction cardiosclerosis (44% and 12 %, respectively; p<0.05), a lower left ventricular ejection fraction (51 [47; 60]% at fQRS-T >80° and 55 [50; 60]% at fQRS-T <80° (p<0,05); 49 [44; 57]% at sQRS-T >110° and 57 [51; 60] % at sQRS-T <110° (p<0.01); more frequent development of acute heart failure (16 and 2 %, respectively; p<0.05); and early postinfarction angina (13 and 2 %, respectively; p<0.05). The increased fQRS-T was associated with a higher incidence of damage to the circumflex artery (45 and 20 %, respectively; p<0.05). The increased sQRS-T was associated with a history of arterial hypertension (97 and 76 %, respectively; p<0.05), chronic heart failure (22 and 3 %, respectively; p<0.05), chronic kidney disease (19 and 4 %, respectively; p<0.05), and a larger myocardial lesion (mean number of damaged segments by echocardiography was 3.8 [2; 6] at sQRS-T >110° and 2.6 [1; 4] at sQRS-T <110°; p<0.01). sQRS-T was significantly greater in multivascular damage (87 [68; 121]° than in one- or two-vascular damage (72 [51; 100]°; p<0.05). sQRS-T values were significantly lower with spontaneous reperfusion (66 [29; 79] than without spontaneous reperfusion (77 [55; 115]°; p<0.05).Conclusion      In patients after inferior wall acute myocardial infarction, increases in fQRS-T and sQRS-T were associated with more severe damage of coronary vasculature, decreased left ventricular ejection fraction, and more severe course of disease.