Author + information
- Received November 18, 1991
- Revision received March 18, 1992
- Accepted March 27, 1992
- Published online September 1, 1992.
- Bodh I. Jugdutt, MBChB, MSc, FACC∗,
- Shou-Bai Tang, MD, MSc,
- Mohammad I. Khan, MBBS and
- Carlos A. Basualdo, MD
- ↵∗Address for correspondence: Bodh I. Jugdutt, MBChB, 2C2.43 Walter Mackenzie Health Sciences Centre, Division of Cardiology, University of Alberta, Edmomon, Alberta, Canada T6G 2R7.
Objectives. This study was undertaken to compare changes in left ventricular remodeling and function during healing after a first anterior non-Q wave versus a Q wave myocardial infarction in the dog.
Background. Whether ventricular remodeling is more severe after anterior Q wave than after anterior non-Q wave infarction has not been studied systematically.
Methods. Serial remodeling and functional variables (two-dimensional echocardiography), electrocardiography and hemodynamic data were recorded over 6 weeks in 58 instrumented dogs subjected to left anterior descending coronary artery ligation or ligation plus collateral obliteration. Postmortem topography and transmurality (by planimetry) and infarct collagen (hydroxyproline) were measured at 6 weeks.
Results. At 6 weeks, infarct collagen was similarly increased in both groups, but the Q wave group had greater infarct size (7.2% vs. 4.5%, p < 0.025) and greater transmurality (88% vs. 58%, p < 0.001), higher left atrial pressures, more infarct expansion (expansion index 2.62 vs. 2.31, p < 0.001), more thinning (thinning ratio 0.62 vs. 0.72, p < 0.001), greater cavity dilation (diastolic volume 88 vs. 72 ml, p < 0.001), more regional bulging in the short-axis view (depth 4.9 vs. 1.9 mm, p < 0.001), more regional asynergy (18% vs. 7%, p < 0.001), lower global ejection fraction (40% vs. 48%, p < 0.001), more endocardial and epicardial bulging in the long-axis view and greater incidence of aneurysm (82% vs. 36%, p < 0.005), left ventricular thrombus (64% vs. 0%, p < 0.0005) and ventricular arrhythmias. Echocardiograms obtained during a 6-week period indicated that left ventricular topographic deterioration and dysfunction were present in the earliest postinfarction study at 2 days in both groups but were more frequent in the Q wave group. Regional myocardial blood flow (24 dogs) was lower in the Q wave than in the non-Q wave group. Scanning electron microscopy (10 dogs) revealed preservation of the epicardial collagen matrix in the non-Q wave but not the Q wave group.
Conclusions. Anterior Q wave infarction is associated with greater transmurality and more postinfarction left ventricular remodeling and dysfunction than is non-Q wave infarction.
☆ This study was supported in part by a grant from the Medical Research Council of Canada, Ottawa, Ontario, Canada.
- Received November 18, 1991.
- Revision received March 18, 1992.
- Accepted March 27, 1992.