A total of 38 AF ablation patients and 38 SVT ablation patients were included in the analysis (all with first follow-up). While the AF subjects were older and more often male, none of the other baseline demographics and cardiovascular risk factors differed between the 2 groups (). None of the demographic or cardiovascular risk factor differences listed in were statistically significant different between the sample study population and consecutive subjects presenting for AF or SVT ablation over the same time period.
Baseline characteristics of subjects with atrial fibrillation (AF) and supraventricular tachycardia (SVT).
Median time to first follow-up amongst AF and SVT patients was 49 days (IQR 37–93) and 48 days (IQR 33–73), respectively (p = 0.36). Twenty-three (61%) of the AF patients and 9 (24%) of the SVT patients returned for second follow-up a median of 179 days (IQR 141–257) and 206 days (IQR 103–339) after enrollment, respectively (p = 0.89 for the comparison in follow-up times).
There was no statistically significant difference in baseline CRP levels between the AF (median 1.8 mg/L, IQR 0.8–5.5) and SVT patients (median 2.5 mg/L, IQR 0.9–5.2), p = 0.65. All AF ablations were performed using radiofrequency energy delivered with an 8 mm tipped catheter. In 31 (82%) of the AF procedures, ablation lines were drawn in 2 circles, each 1–2 cm outside and encompassing the left or right pulmonary veins, and the remaining 7 underwent ablations 1–2 cm outside and encompassing each of the individual veins. In addition, fractionated electrocardiograms were targeted in 22 (58%), and 6 (16%) underwent ablation from the left lower pulmonary vein to the mitral valve isthmus. Of the 38 SVT patients, 18 had typical AV nodal reentrant tachycardia (AVNRT), 9 had atrioventricular reciprocating tachycardia, 6 had focal atrial tachycardia, 1 had atypical AVNRT, 1 had junctional tachycardia, and 3 failed to exhibit an inducible tachycardia. Of these, radiofrequency energy was used in 29 (28 with a 4 mm tipped catheter and 1 with an 8 mm catheter), cryoablation was used in 4, and ablation was not performed in 2 parahisian atrial tachycardias as well as the 3 cases wherein the clinical tachycardia could not be induced. Compared to the SVT ablations, AF ablations involved significantly more radiofrequency applications (69 ± 33 versus 13 ± 13, p<0.001), longer total ablation time (median 1,911 seconds, IQR 1,420-2,735 versus median 416 seconds, IQR 180–669, p<0.001) and higher mean power (41 ± 9 Watts versus 31 ± 15 Watts, p=0.0051).
CRP levels significantly increased from baseline to first follow-up in the AF ablation group (). CRP levels did not significantly change in the SVT group. Those with a rise in CRP after ablation were older than those without, but none of the other baseline demographics or cardiovascular risk factors were significantly associated with a rise or fall in CRP (). Among the AF patients, the type of AF ablation did not significantly influence the change in CRP, and, among the SVT patients, the type of SVT ablation did not meaningfully influence the change in CRP. A sensitivity analysis was performed excluding the SVT subjects that did not undergo RF ablation, and the findings did not meaningfully change the results (no significant change in CRP was observed after excluding these patients). In the 4 SVT patients treated with cryoablation, 3 exhibited an increase in CRP and 1 exhibited a decrease.
Median levels of CRP after atrial fibrillation and supraventricular tachycardia ablation. See text for median time to first and second follow-up visits. Y error bars denote interquartile ranges of CRP.
Baseline demographics of AF and SVT subjects with either a rise or fall in CRP between baseline and first follow-up visits. No subject exhibited identical CRP levels on these 2 visits.
None of the individual ablation parameters (total number of ablations, total ablation time, or mean power delivered) were significantly associated with the change in CRP from baseline to first follow-up in bivariate analysis. However, in logistic regression analysis adjusting for each of these variables, an 8 mm ablation catheter ablator size was associated with a greater odds of an increase in CRP (odds ratio [OR] 8.5, 95% confidence interval [CI] 1.07–68.0, p=0.043).
Of the 38 AF patients, 17 had evidence of recurrent AF prior to their first follow-up visit (10 with documented AF and 7 with symptoms consistent with AF that were the same or worse than prior to their procedure). Examining only those with early recurrent AF (AF detected by the time of first follow-up), median CRP significantly increased (). In contrast, the median CRP decreased after AF ablation in those without evidence of AF recurrence at first follow-up; importantly, in those without early recurrence of AF, the overall distribution of CRP increased to a nearly statistically significant degree (as can be seen by the increase in the interquartile range in , p=0.050).
Figure 2 Median baseline and first follow-up CRP levels of atrial fibrillation ablation patients with and without evidence of recurrent atrial fibrillation by first follow-up. Solid and dashed Y error bars denote interquartile ranges for those with and without (more ...)
Although a larger proportion of subjects with AF recurrence prior to first follow-up exhibited an increase in CRP (77%) compared to those without any known AF recurrence (67%), this difference was not statistically significant in the bivariate analysis (p=0.51). After adjusting for multiple potential confounders, including age, gender, body mass index (BMI), statin therapy, and antiarrhythmic agents, those with recurrence of AF prior to first follow-up had a statistically significant greater odds of having an increase in CRP (OR 21, 95% CI 1.1–417, p=0.045).
A total of 33 AF ablation patients were interviewed either during their second follow-up visit or by phone a median 194 days (IQR 146–271) after their procedure. Of these, 22 had an improvement or elimination of symptoms (approximately half of these with complete elimination). There was no correlation with a rise in CRP and change in symptoms.