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Contractile reserve of dysfunctional myocardium after revascularization: a dobutamine stress echocardiography study
A Lombardo1, F Loperfido, C Trani
1Institute of Cardiology, Catholic University Sacro Cuore, Rome, Italy.
Insights
Revascularization maintains or increases contractile reserve in dysfunctional heart muscle, even in areas not expected to recover. This preserved reserve may improve patient outcomes after treatment.
Area of Science:
- Cardiology
- Cardiovascular Medicine
- Myocardial Viability Assessment
Background:
- Improvement in dysfunctional but viable myocardium post-revascularization is often less than anticipated based on dobutamine stress echocardiography findings.
- The fate of contractile reserve in myocardial segments that do not adequately recover function after revascularization remains unclear.
Purpose of the Study:
- To investigate the impact of revascularization on the contractile reserve of dysfunctional myocardium.
- To understand the changes in myocardial contractile reserve in post-infarction patients after revascularization procedures.
Main Methods:
- Dobutamine stress echocardiography was used to assess basal contraction and contractile reserve in infarct zones of 21 post-infarction patients before and after revascularization.
- Wall motion score index (WMSI) was calculated to quantify regional myocardial function.
Main Results:
- Contractile reserve was present in 14 infarct zones and absent in 16 zones before revascularization.
- After revascularization, ejection fraction improved in patients with pre-existing contractile reserve.
- Contractile reserve persisted in 93% of zones with prior reserve and developed in 38% of zones without prior reserve, though recovery was limited in the latter group.
Conclusions:
- Contractile reserve is maintained or enhanced in viable infarct zones post-revascularization, even without immediate functional recovery.
- Contractile reserve can emerge in previously non-viable infarct zones, suggesting potential for improved function.
- The maintenance and development of contractile reserve after revascularization may contribute to overall functional improvement in patients.
Objectives:
We sought to investigate the effects of revascularization on the contractile reserve of dysfunctional myocardium.
Background:
The improvement in dysfunctional but viable myocardium after revascularization is frequently less than expected from the amount of contractile reserve detected on dobutamine stress echocardiography. The fate of the contractile reserve, when it does not result in an adequate contractile recovery, is unknown.
Methods:
Basal contraction and contractile reserve of infarct zones were assessed by dobutamine stress echocardiography in 21 postinfarction male patients before and > 3 months after revascularization (30 infarct zones; mean +/- SD left ventricular ejection fraction 35 +/- 8%). An infarct zone wall motion score index (WMSI) was calculated.
Results:
Before revascularization, contractile reserve was present in 14 infarct zones (12 patients) and absent in 16 (9 patients). After revascularization, ejection fraction increased by 5 +/- 4% (p < 0.01) in patients classified as positive for contractile reserve and remained unchanged in those classified as negative. New York Heart Association classification improved in 58.3% and 22.2% of patients, respectively. Basal contraction improved in eight zones with previous contractile reserve (57.1%) and in one zone without (6.3%) (p < 0.01). Contractile reserve was still evident in 13 zones with previous contractile reserve (93%; 8 with contractile recovery), and it developed in 6 zones without (38%; none with contractile recovery). WMSI values after revascularization were decreased from values before revascularization during low dose dobutamine in zones with and without previous contractile reserve (p < 0.01 and < 0.05, respectively).
Conclusions:
After revascularization, contractile reserve is maintained or even increases in viable infarct zones that do not recover as expected. It may also develop in some infarct zones judged not to be viable before revascularization. This increased contractile reserve may play a role in the functional improvement of patients after revascularization.