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Left Axis Deviation: Diagnostic Contribution of Exercise Stress Testing

1973; Elsevier BV; Volume: 63; Issue: 2 Linguagem: Inglês

10.1378/chest.63.2.159

1931-3543

Alan B. Miller, John Naughton, Patrick A. Gorman,

Cardiac Imaging and Diagnostics

The significance of left axis deviation (LAD) in the frontal plane in otherwise healthy patients is controversial. This study was performed to determine the effects of graded multistaged treadmill exercise on the ECG responses of 20 patients with isolated LAD (study group) and of 20 age matched patients with an axis which ranged from +5° to +80° in the frontal plane (control group). A 12 lead ECG was recorded at supine rest, and a single lead ECG (CM5) was recorded while standing, throughout exercise and during the first five minutes of recovery. Blood pressure was measured by the auscultatory technique during each minute of the study. A displacement of the ST segment of 0.1mV or greater lasting for 0.08 sec or longer, conduction abnormalities, the appearance of ten or more premature ventricular contractions (PVC's)/min, or an abnormal systolic blood pressure response characterized an abnormal exercise test The mean age of the study group was 51.5 years and of the control group 50.1 years. Fourteen patients (70 percent) in the study group had abnormal exercise tests compared with eight patients (40 percent) in the control group (p<0.08). Ischemic ST changes were recorded in seven (35 percent) of the LAD patients and in three (15 percent) of the control subjects (p<0.05), while PVCs were recorded in 30 percent of the study group and in 5 percent of the controls (p<0.05). One patient in the control group developed complete LBBB during exercise. No other ECG abnormalities were documented in either group. Abnormal systolic Mood pressure responses were noted in four patients (20 percent) in the study group and in two patients (10 percent) in the control group. These data suggest that isolated LAD is not necessarily a benign finding, and that the performance of an exercise stress test is helpful in defining its clinical significance more precisely. The significance of left axis deviation (LAD) in the frontal plane in otherwise healthy patients is controversial. This study was performed to determine the effects of graded multistaged treadmill exercise on the ECG responses of 20 patients with isolated LAD (study group) and of 20 age matched patients with an axis which ranged from +5° to +80° in the frontal plane (control group). A 12 lead ECG was recorded at supine rest, and a single lead ECG (CM5) was recorded while standing, throughout exercise and during the first five minutes of recovery. Blood pressure was measured by the auscultatory technique during each minute of the study. A displacement of the ST segment of 0.1mV or greater lasting for 0.08 sec or longer, conduction abnormalities, the appearance of ten or more premature ventricular contractions (PVC's)/min, or an abnormal systolic blood pressure response characterized an abnormal exercise test The mean age of the study group was 51.5 years and of the control group 50.1 years. Fourteen patients (70 percent) in the study group had abnormal exercise tests compared with eight patients (40 percent) in the control group (p<0.08). Ischemic ST changes were recorded in seven (35 percent) of the LAD patients and in three (15 percent) of the control subjects (p<0.05), while PVCs were recorded in 30 percent of the study group and in 5 percent of the controls (p<0.05). One patient in the control group developed complete LBBB during exercise. No other ECG abnormalities were documented in either group. Abnormal systolic Mood pressure responses were noted in four patients (20 percent) in the study group and in two patients (10 percent) in the control group. These data suggest that isolated LAD is not necessarily a benign finding, and that the performance of an exercise stress test is helpful in defining its clinical significance more precisely.