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6.2.2 Asymptomatic Patients With Pre-Excitation: Recommendations

Recommendations for Management of Asymptomatic Patients With Pre-Excitation COR LOE Recommendations

I B-NR SR 1.  In asymptomatic patients with pre-excitation, the findings of abrupt loss of conduction over a manifest pathway during exercise testing in sinus rhythm294–297 (Level of Evidence: B-NR) SR or intermittent loss of pre-excitation during ECG or ambulatory monitoring297 (Level of Evidence: C-LD) SR are useful to identify patients at low risk of rapid conduction over the pathway. C-LD SR

See Online Data Supplements 11 and 12. Noninvasive testing has been shown to identify patients at low risk of developing rapid conduction over the accessory pathway and life-threatening ventricular arrhythmias in response to AF. The noninvasive findings that identify a pathway not capable of maintaining rapid conduction during AF include intermittent loss of conduction over the accessory pathway on the resting ECG or during ambulatory monitoring, or abrupt loss of pre-excitation during exercise testing (Figure 16).294–297 The ECG should be evaluated closely to make certain the delta wave is truly absent, as accessory pathways, especially left lateral pathways, may demonstrate varying degrees of pre-excitation because of fusion between conduction over the accessory pathway and through the AV node. This may give the appearance of loss of pre-excitation if the subtle delta wave is not identified. Noninvasive tests have an approximately 90% positive predictive value and 30% negative predictive value for identifying pathways with life-threatening properties.294,295,297

IIa B-NR SR 1.  An EP study is reasonable in asymptomatic patients with pre-excitation to risk-stratify for arrhythmic events.254,256,298–301

See Online Data Supplements 11–15. In the absence of symptoms, a clinical priority is identifying accessory pathways at increased risk of arrhythmic events, including rapid conduction during AF and development of life-threatening ventricular arrhythmias, with the most useful findings being the following: an R-R interval <250 ms between 2 pre-excited complexes during induced AF; the presence of multiple accessory pathways; the ability to induce sustained AVRT; the finding of AVRT precipitating pre-excited AF; and an accessory pathway refractory period <240 ms.254,256,298,299,301 Malignant arrhythmias correlate more with the EP properties of the accessory pathway than with the presence or absence of symptoms. This approach is supported by the low risk of complications observed in an EP study in which complication rates among 2169 patients ranged from 0.09% to 1% and included pneumothorax and access site complications.254

IIa B-NR SR 2.  Catheter ablation of the accessory pathway is reasonable in asymptomatic patients with pre-excitation if an EP study identifies a high risk of arrhythmic events, including rapidly conducting pre-excited AF.254,302,303

See Online Data Supplements 11–15. In a large prospective cohort study of 756 asymptomatic patients with close to 8 years of follow-up, 9% of patients developed malignant AF (shortest R-R interval ≤250 ms), and 2% developed ventricular fibrillation.254 Malignant arrhythmias correlated more with high-risk EP properties of the accessory pathway than with the presence or absence of symptoms. Ablation of the accessory pathway(s) in high-risk patients was also examined in 1 RCT that enrolled 76 patients, showing that arrhythmic events (defined as symptomatic SVT, AF, and ventricular fibrillation in this study) occurred in 7% of patients who underwent ablation versus 77% who did not undergo ablation.302 Another study that examined patients on the basis of whether an ablation was performed reported that none of the asymptomatic patients who had undergone ablation of the accessory pathway developed a malignant arrhythmia during 8 years of follow-up. The risk of complications with ablation ranged from 0.1% (complete heart block) to 0.9% (ablation-induced right bundle-branch block).254 The risks and benefits of proceeding with ablation of pathways found not to have high-risk characteristics should be discussed thoroughly with patients in advance of the EP procedure.

IIa B-NR SR 3.  Catheter ablation of the accessory pathway is reasonable in asymptomatic patients if the presence of pre-excitation precludes specific employment (such as with pilots).103,254,276–282,302–304

See Online Data Supplements 11–15. Patients with asymptomatic pre-excitation whose job activities would place them or others at risk if a hemodynamically significant arrhythmia occurred (such as airline pilots) are potential candidates for catheter ablation. Catheter ablation is associated with a success rate of approximately 95% and a 3% risk of major complications when patients are followed up for 6 months to 8 years.103,254,276–282,302,303 Other documents advise EP study in asymptomatic athletes who engage in moderate- or high-level competitive sports.305 IIa B-NR SR 4.  Observation, without further evaluation or treatment, is reasonable in asymptomatic patients with pre-excitation.301,306–309

See Online Data Supplements 11–15. Most observational cohort studies suggest that the great majority of adult patients with asymptomatic pre-excitation who do not undergo an ablation of the accessory pathway have a benign course with few clinically significant arrhythmic events occurring over time. This supports the recommendation that observation without medical therapy or ablation is a reasonable alternative because the risk of SCD is small and is seen mainly in children.254,301,306–309 The choice to observe asymptomatic patients should be preceded by the patient being informed of the small risk of life-threatening arrhythmias developing in the absence of treatment, along with the success rate and complications associated with catheter ablation of the accessory pathway.

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