4-1 Major findings
We found that 1) coronary artery disease was incidentally detected in 3.6 % of patients undergoing ablation for atrial fibrillation; 2) HbA1c ³ 6.1% and HDL-chol £ 4.9 mg/dL were predictors of incidentally detected coronary artery disease in patients undergoing ablation for atrial fibrillation.
4-2. Incidental coronary artery detection rate in patients undergoing ablation for atrial fibrillation
In recent years, ablation for atrial fibrillation has often been performed before medical therapy. The reason for this is based on findings from three randomized controlled trials3-5 and their summary analyses6, which showed significantly higher rates of atrial fibrillation resolution and similar rates of complications in the ablation group. Catheter ablation may be an appropriate first-line treatment for patients with symptomatic paroxysmal atrial fibrillation.
Coronary artery disease may be found incidentally when coronary angiography is performed during atrial fibrillation ablation, which has been increasing in recent years. Hypertension, diabetes, obesity, and smoking have also been reported as clinical risk factors for atrial fibrillation1, 7-9. These factors overlap with the clinical risk factors for coronary artery disease, and coronary artery disease is also reportedly found in 30% of patients with atrial fibrillation10. However, the extent to which coronary artery disease is present in patients undergoing ablation for atrial fibrillation has not been studied in detail. Therefore, we examined the extent to which such incidental findings of coronary artery disease are detected and the predictors of such disease. We found that CAD was found incidentally in 3.63% of patients undergoing atrial fibrillation ablation. In the past, such data have been largely lacking. However, 43 patients did not undergo coronary artery evaluation at the discretion of the ablating physician, so the detection rate in this study may not represent the true detection rate.
4-3. Predictors of incidental coronary artery detection in patients undergoing ablation for atrial fibrillation
The CHADS2 score is used to assess the risk of cerebral infarction in patients with atrial fibrillation, and is also used as a predictor because the score contains risk factors overlapping with those for coronary artery disease. We therefore investigated whether the CHADS2 score offers a predictor of incident coronary artery disease in patients with ablation of atrial fibrillation. CHADS2 score was significantly higher in the ABL-CAD group (1.8 ± 1.2) than in the ABL-non-CAD group (1.0 ± 0.95). CHADS2 score was identified as a possible predictor in univariate analysis, but did not remain after multivariate analysis (Table 2). In addition, each of the CHADS2 factors of heart failure, hypertension, age, and diabetes differed significantly different groups and were possible predictors in univariate analysis, but considering that none remained in multivariate analysis, the finding that CHADS2 score did not remain as a predictor is reasonable. HbA1c ³ 6.1% and HDL £ 49 mmHg were found to be predictors in multivariate analysis. HbA1c ³ 6.1% is a value reflecting glucose intolerance17, and HDL £ 49 mmHg is also a clinically low value. Since the risk of cardiovascular mortality tends to decrease with lower HDL values19, this represents a clinically plausible incidental coronary predictor. The ROC curves for age alone and for age plus HbA1c ³ 6.1% plus HDL-chol £ 49 mg/dL were tested by logistic regression analysis, showing a significant difference, with a greater AUC for age + Hba1c ³ 6.1% + HDL £ 49 mg/dL (0.810) than for age alone (0.672, P = 0.005) (Figure 2). The results for this multivariate ROC predict that incidental coronary artery disease would be detected during ablation with greater accuracy if the patient shows both Hba1c ³ 6.1% and HDL £ 49 mg/dL.
4-4. Clinical implications
These results indicate that patients undergoing ablation for atrial fibrillation have significant coronary artery stenosis, at a rate of 3.6%, with Hba1c and HDL as predictors. In particular, patients with HbA1c ³ 6.1% and HDL £ 49 mg/dL are more likely to have significant coronary artery stenosis, and coronary angiography is recommended during atrial fibrillation ablation for patients with these conditions.
One advantage of being alert to the presence of coronary artery disease prior to ablation is that the risk of hemodynamic compromise due to ischemia can be determined during ablation. Another advantage is that, depending on the form of the coronary artery disease, a decision can be made as to whether ablation or PCI should be performed first. In addition, ablation significantly improves the prognosis of heart failure with atrial fibrillation compared to medical therapy20, and the number of ablations is expected to increase in the future. Therefore, the importance of evaluations including the coronary arteries is expected to increase, and coronary artery evaluation will become more important at the time of ablation in patients who display the above factors.
4-5. Limitations
First, this study was a single-center study using a retrospective design. Second, we included patients without chest pain who underwent ablation for atrial fibrillation, rather than the entire population of patients undergoing ablation, such as those undergoing ablation for paroxysmal supraventricular tachycardia or premature ventricular contractions. Third, for 43 patients, the ablation physician decided that coronary angiography was not necessary at the same time as the ablation procedure for atrial fibrillation. The reason for this decision was probably that the ablation physician did not perform the procedure in patients lacking coronary risk factors, but the actual reasons could not be determined from the information left in the medical records. If coronary angiography had been performed in these patients and included in the study, the incidence rate and predictors would most likely have changed.