About one fourth of patients (pts) with coronary artery disease (CAD) referred for coronary bypass surgery (CABG) exhibits some kind of intraventricular conduction defect (IVCD).
Objective: To assess CABG influence on the behavior of intraventricular conduction in pts submitted to CABG.
Material and methods: Prospective study of 504 pts with severe CAD (3-vessel and/or left main trunk disease), divided in 2 groups (Gr) - GrA, composed of 252 pts with on-pump CABG, and GrB, with 252 pts submitted to off-pump CABG - whose pts were matched for age, gender, angiographic data, additive Euroscore, prior myocardial infarction, diabetes and hypertension. Other data (GrA vs GrB): nr of bypasses/pt 2.9 vs 2.4 (p<0.01); bypass to LAD 100% vs 100%; complete revascularization 60% vs 60%; left ventricular dysfunction 39% vs 34% (NS). Electrocardiographic study: pre-operative 12-lead ECG (within 72 hrs prior to CABG); post-operative (post-op) continuous ECG monitoring by telemetry (1 lead), including recording of data, until the discharge; post-op 12-lead ECG (up to 24 hrs after CABG), eventually repeated accordingly to the telemetric ECG evolution; ECG recordings were always performed by the same technician, with the same ECG recorder (25 mm/sec; 1 mV=10 mm). Results (GrA vs GrB): 1) Pre-operative IVCD 27% vs 24% (NS). 2) Post-op regression/abolition of IVCD (due to reversion of chronic stunning of the conduction system) 24%vs 28% (NS), occurring shortly (up to 24 hrs) after CABG termination in 95% of cases. IVCD aggravation/new IVCD 9.9% vs 0.8% (p<0.001). 3) Post-op IVCD: global figure 28% (+4.5%) vs 21% (-13%), p>0,05; stable IVCD + aggravated IV conduction 30% vs 18% (p<0.01). Post-op permanent pacing: 2 pts vs 0 pts.
Conclusions: 1) A significant number (at least 24%) of pts with severe CAD and stable IVCD shows chronic ischemic stunning of the IV conduction system, which reverts after CABG. 2) Off-pump CABG (in opposition to on-pump CABG), by assuring a better intra-operative protection of the ventricular septum, promotes an improvement of intraventricular conduction in pts submitted to CABG.