Author + information
- Received October 29, 1986
- Revision received March 25, 1987
- Accepted June 12, 1987
- Published online November 1, 1987.
- ↵*Address for reprints: Hiroshi Tsunakawa, MD, Division of Cardiology, Showa University Fujigaoka Hospital, 1-30 Fujigaoka, Midori-ku, Yokohama 227, Japan.
The residue value on dipole analysis (the ratio of nondipolar component to the measured body surface potentials) was estimated mathematically in 16 patients with left bundle branch block. Patients were classified into those with (group A, nine patients) and those without (group B, seven patients) a perfusion defect on thallium-201 myocardial scintigraphy. For the entire QRS complex the residue of group B was smaller than that of normal subjects (20.0 ± 4.1% versus 24.6 ± 3.5%, p < 0.05). Group A showed a greater mean residue value than group B (27.4 ± 4.4% versus 20.3 ± 2.4%, p < 0.01) only during the initial one-third of the QRS complex. All but one patient of group A and only one patient in group B showed a high peak on the residue curve during the initial stage of the QRS complex. The maximal residue value of group A during the initial QRS complex was significantly greater than that of group B (40.9 ± 10.9% versus 23.4 ± 5.4%, p < 0.01). An arbitrarily selected criterion of the maximal residue value ≥30% during the initial QRS complex showed a sensitivity of 89% with a specificity of 86% for the diagnosis of myocardial infarction in the presence of left bundle branch block.
These results might be related to the complex ventricular activation around the infarcted area even in the presence of left bundle branch block in which intramyocardial conduction with a simple activation front predominates. Dipole analysis appeared to be a valuable method of diagnosing myocardial infarction in the presence of left bundle branch block.
- Received October 29, 1986.
- Revision received March 25, 1987.
- Accepted June 12, 1987.
- American College of Cardiology Foundation