Coronary complexity and reversibility of complete atrioventricular block in ischemic heart disease: the predictive role of the SYNTAX score

Background Complete atrioventricular block (AVB) is a serious complication of ischemic heart disease that may require temporary cardiac pacing. Although AV block occurring during acute myocardial infarction, particularly inferior infarction, is often reversible after reperfusion, predictors of atrioventricular conduction recovery remain poorly defined. Coronary anatomical complexity assessed by the SYNTAX score reflects the severity of coronary artery disease and may influence the reversibility of ischemia-related conduction disturbances. Purpose To evaluate the association between coronary anatomical complexity, assessed by the SYNTAX score, and recovery of atrioventricular conduction in patients presenting with complete atrioventricular block in the setting of ischemic heart disease. Methods We conducted an observational study including consecutive patients presenting with complete AV block and angiographically confirmed coronary artery disease. Clinical, electrocardiographic, echocardiographic and biological data were collected. Coronary complexity was assessed using the SYNTAX score. Culprit artery location, completeness of revascularisation and delay to revascularisation were analysed. The primary endpoint was recovery of atrioventricular conduction during hospitalisation. Multivariable logistic regression analysis identified independent predictors of conduction recovery. Results A total of 131 patients presenting with complete atrioventricular block in the setting of acute coronary syndrome underwent coronary angiography with or without PCI (mean age 64±12 years, 70% men). Inferior myocardial infarction was the most frequent presentation, and temporary pacing was required in most patients at admission. Recovery of AV conduction occurred in 46 patients (35%). Patients with reversible AV block had significantly lower SYNTAX scores than those with persistent block (11.9±6.3 vs 23.5±9.1; p<0.001). Recovery was more frequent in patients with right coronary artery involvement, complete revascularisation, and early revascularisation. In multivariable analysis, the SYNTAX was independently associated with AV block reversibility (OR 0.87 per point increase; 95% CI 0.82–0.93; p<0.001). A SYNTAX ≤14 predicted AV conduction recovery with good discriminative performance (AUC=0.81), whereas scores >22 were associated with a markedly higher probability of persistent AV block requiring permanent pacemaker implantation (PPI). Conclusions Coronary anatomical complexity assessed by the SYNTAX score is strongly associated with reversibility of complete AV block in ischemic heart disease and carries prognostic implications. Low SYNTAX score identify patients with a high probability of atrioventricular conduction recovery after revascularisation, whereas higher scores are associated with persistent AV block requiring PPI.These findings may help identify patients in whom permanent pacing can be safely deferred after revascularisation.