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[Postoperative changes in perfusion scintigraphic picture in patients with previous myocardial infarct]
M Galli1, W Bencivelli, N F Pardo
1Divisione di Cardiologia, Fondazione Clinica del Lavoro, Centro Medico di Riabilitazione, Veruno, Novara.
Insights
Coronary artery bypass grafting (CABG) improved myocardial perfusion in patients with previous myocardial infarction (MI). Reversible thallium defects predicted better outcomes post-CABG, irrespective of Q waves.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Cardiac Surgery
Background:
- Previous myocardial infarction (MI) is a significant risk factor for cardiac events.
- Coronary artery bypass grafting (CABG) is a common surgical intervention for patients with ischemic heart disease.
- Assessing myocardial perfusion is crucial for evaluating the effectiveness of revascularization strategies.
Purpose of the Study:
- To evaluate the impact of CABG on myocardial perfusion patterns in patients with prior MI.
- To determine if pre-operative thallium uptake patterns predict post-CABG functional recovery.
- To correlate surgical outcomes with specific scintigraphic findings.
Main Methods:
- Studied 44 patients with previous MI undergoing CABG.
- Utilized thallium-201 scintigraphy (effort or dipyridamole test) to assess myocardial uptake before and after surgery.
- Classified 9 myocardial segments per patient as normal, reversible defect, or irreversible defect.
- Correlated scintigraphic findings with clinical outcomes and ECG parameters (Q waves).
Main Results:
- CABG significantly reduced angina incidence (16% vs 77%) and ST-segment depression (20% vs 78%).
- 47% of abnormal myocardial segments showed improvement or normalization post-CABG.
- Reversible thallium defects demonstrated a significantly better improvement rate (68%) compared to irreversible defects (27%).
- Improved perfusion was significantly greater in revascularized segments (p < 0.0005).
- No correlation was found between Q-wave presence and surgical outcome.
Conclusions:
- CABG effectively improves myocardial perfusion in patients with previous MI.
- The presence of reversible thallium defects is a strong predictor of improved regional myocardial perfusion after CABG.
- Scintigraphic assessment of reversible defects is valuable for predicting functional recovery post-revascularization, independent of Q-wave presence.
Abstract:
In 44 patients with previous MI who underwent CABG, we studied the effect of surgical reperfusion by comparing the different patterns of Thallium uptake after effort or dipyridamole test. For each patient, 9 myocardial segments were classified either normal or abnormal for reversible or irreversible uptake defect, both before and after surgery. CABG (complete in 77% of patients) reduced the incidence of angina (16% vs 77% pre-CABG, p less than 0.001) and of significant (greater than 1 mm) ST-segment depression during the test (20% vs 78%, p less than 0.001). Of 235/496 abnormal segments, 111 (47%) normalised or improved after CABG while an impairment was observed in 34/277 (12%) normal segments or with reversible defect at pre-CABG scan (p less than 0.001). Reversible defects showed a far better outcome relative to irreversible defects: an improvement was achieved in 68% of the former instances, vs only in 27% of the latter (p less than 0.001). Among the 264 myocardial segments which can be ascribed consistently to the territory of some particular coronary vessel, a significantly greater incidence of post-CABG improvement was found in revascularized segments (60/195 vs 5/69, p less than 0.0005). On the contrary it was not possible to correlate the surgery outcome with the presence of ECG Q-waves in the segment. Thus the presence of reversible Thallium defects in post MI patients predicts the improvement of regional perfusion pattern after CABG, regardless of the presence of Q waves.(ABSTRACT TRUNCATED AT 250 WORDS)