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Significance of coronary artery bypass grafting-associated conduction defects
P Mustonen1, M Hippeläinen, E Vanninen
1Department of Surgery, Kuopio University Hospital, Finland.
Insights
Permanent conduction defects (CDs) after coronary artery bypass grafting (CABG) do not significantly impact long-term mortality or major events. However, patients with CDs experience reduced left ventricular function and more exercise-limiting symptoms like chest pain or dyspnea.
Area of Science:
- Cardiovascular Surgery
- Cardiac Electrophysiology
- Clinical Outcomes Research
Background:
- Coronary artery bypass grafting (CABG) can lead to permanent atrioventricular conduction defects (CDs).
- The long-term clinical impact of these CDs following CABG is not well-established.
Purpose of the Study:
- To compare the 3-year clinical outcomes of patients with permanent CABG-associated CDs (CD+) versus those without CDs (CD-).
- To assess the effects of CDs on mortality, cardiac events, neurologic events, functional capacity, and left ventricular systolic function.
Main Methods:
- A cohort study comparing 52 patients with permanent CABG-associated CDs to 47 patients without CDs.
- Follow-up duration was 3 years.
- Outcomes assessed included mortality, cardiac/neurologic events, work capability, exercise capacity, left ventricular ejection fraction (LVEF), and signal-averaged electrocardiograms.
Main Results:
- No significant differences in late mortality, cardiac events, neurologic events, or work capability between CD+ and CD- groups.
- Patients with CDs reported more frequent chest pain or dyspnea as exercise-limiting symptoms.
- Lower resting and submaximal LVEF were observed in the CD+ group.
- CD+ patients with left bundle branch block or pacemaker had significantly lower LVEF at maximal workload.
Conclusions:
- Clinical outcomes are comparable between patients with and without CABG-associated CDs at 3-year follow-up.
- Patients with CDs exhibit reduced left ventricular systolic function.
- Chest pain and dyspnea are more common exercise-limiting symptoms in patients with CDs post-CABG.
Abstract:
The incidence of permanent atrioventricular conduction defects (CDs) caused by coronary artery bypass grafting (CABG) varies from 5% to 43% if cold crystalloid or blood cardioplegia is used for myocardial preservation. However, the long-term effects of CDs on clinical outcome are not well known. In this study we compared the outcome of 52 patients with permanent CABG-associated CDs (CD+) to 47 patients without CDs (CD-) after a 3-year follow-up. Recovery of CDs was found in 2 patients during the follow-up. There were no significant differences between groups in late mortality, cardiac or neurologic events, or capability to work. Although exercise capacity was similar, the exercise-limiting symptom more often was chest pain or dyspnea in the CD+ group than in the CD- group (p = 0.001). Left ventricular ejection fractions at rest and at 50-W workload level were lower in the CD+ group (p = 0.03 to 0.05). In addition, CD+ patients with left bundle branch block or cardiac pacemaker had significantly lower ejection fraction at maximal workload level than patients without CDs (p = 0.03). No significant differences were observed between the groups in the potential risk for ventricular arrhythmias according to signal-averaged electrocardiograms. In conclusion, the clinical outcome of patients with CDs after CABG operations is almost comparable to those without CDs during a 3-year follow-up. However, patients with CDs have lower left ventricular systolic function and more often have chest pain or dyspnea as the exercise-limiting symptom than patients without CDs.