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Serial changes in left ventricular function after coronary artery bypass: implications in viability assessment
1Philadelphia Heart Institute, Presbyterian Medical Center, PA 19104.
Insights
Assessing left ventricular (LV) ejection fraction (EF) after bypass surgery is crucial. For patients with LV dysfunction, EF improves significantly over time, with late assessments revealing greater recovery than early ones.
Area of Science:
- Cardiology
- Cardiac Surgery
- Diagnostic Imaging
Background:
- Left ventricular (LV) performance post-coronary artery bypass surgery (CABS) is a key indicator of myocardial viability.
- The temporal dynamics of LV functional recovery after CABS are not fully understood.
Purpose of the Study:
- To evaluate the changes in LV ejection fraction (EF) at early and late time points after CABS.
- To compare EF changes in patients with normal preoperative LV function versus those with preoperative LV dysfunction.
Main Methods:
- Gated blood pool imaging was used to measure LV ejection fraction (EF).
- Patients were divided into two groups: normal preoperative EF (n=12) and LV dysfunction (n=15).
- EF was assessed preoperatively, early postoperatively (6 days), and late postoperatively (62 days).
Main Results:
- Patients with normal preoperative EF showed no significant change in EF post-CABS.
- Patients with LV dysfunction demonstrated a significant increase in EF from pre- to late postoperative assessment (26% to 34%, p < 0.05).
- The proportion of patients with >=5% EF improvement increased from 4 early to 11 late postoperatively (p < 0.05).
Conclusions:
- The timing of EF assessment is critical for evaluating myocardial recovery in patients with LV dysfunction post-CABS.
- Early postoperative EF measurements may underestimate the extent of functional improvement.
- Late assessment provides a more accurate picture of overall LV recovery after bypass surgery.
Abstract:
Improvement in left ventricular (LV) performance after coronary artery bypass surgery remains the gold standard in myocardial viability assessment. The time-related changes, however, are not well known. This study examined the LV ejection fraction (EF) by gated blood pool imaging early (6 +/- 4 days) and late (62 +/- 24 days) after surgery in patients with normal preoperative EF (group 1, n = 12) and those with LV dysfunction (group 2, n = 15). There were no changes in the clinical status between the early and late studies, and all patients had normal sinus rhythm. Group 1 had no significant change in EF (preoperatively 62%, early postoperatively 64%, late postoperatively 63%; p = NS). In group 2, EF was 26% +/- 8% preoperatively; 30% +/- 10% early postoperatively; and 34% +/- 8% late postoperatively (p < 0.05). Postoperatively there was > or = 5% improvement in EF in 4 patients early and 11 patients late (p < 0.05). Patients who showed early improvement continued to do so in the late study but, additionally, 7 patients showed improvement only in the late study. Thus the timing of EF measurement after surgery is important in patients with LV dysfunction but not in patients with normal LV function. Early assessment may underestimate the prevalence and degree of recovery.