Pulmonary vein isolation does not alter cardiovascular afferent autonomic reflexes in atrial fibrillation

Abstract

Background: Pulmonary vein isolation (PVI) remains the cornerstone of atrial fibrillation (AF) ablation. We previously demonstrated abnormal cardiac volume-sensitive reflexes (whose receptors are co-located in veno-atrial tissue) in AF patients. Whether PVI disrupts afferent nerves is unknown.

Objectives: Evaluate whether PVI disrupts afferent volume-sensitive reflexes.

Methods: We consecutively studied autonomic reflexes in AF patients undergoing PVI, repeating the study post-PVI, if AF-free >6 months. We excluded patients with AF recurrence/procedural complications, allowing repeat procedures. We measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR) continuously during low-level Lower Body Negative Pressure (LBNP), at 0, -20 and -40 mmHg (predominantly testing volume baroreceptors); Valsalva reflex (predominantly arterial baroreceptors); and Isometric Handgrip reflex (IHR, both). LBNP produces reflex vasoconstriction, evaluated from forearm blood flow (FBF ∝ 1/vascular resistance).

Results: 18 patients were studied pre-PVI; n = 9 completed both visits. Mean age was 64 ± 3 years (78% male); BMI 28 ± 1 kg/m²; LA size 37 ± 2 mL/m²; and left ventricular function 65 ± 3%. Despite alterations in heart rate variability (HRV), there was no difference in IHR, Valsalva, or LBNP responses pre- versus post-PVI. During LBNP, MAP decreased slightly both pre- (-1.6 ± 3%) and post-PVI (-2.8 ± 1.8%); p = .7. HR increased similarly (p = .7) pre- (10.6 ± 6.4%) and post-PVI (7.2 ± 1.5%). FBF response was unchanged (p = .8). Resting (arterial) baroreflex sensitivity was unaltered.

Conclusion: PVI does not impair cardiovascular reflexes involving afferent baroreceptors, suggesting HRV changes reflect efferent modulation or ablation adequacy rather than afferent disruption. Whether disrupting sino-atrial efferent nerves represents a marker of adequate ablation or influences PVI outcomes requires evaluation.

Keywords: Valsalva reflex; atrial fibrillation; autonomic nervous system; isometric handgrip reflex; lower body negative pressure.

FIGURE 1

CONSORT Diagram of patient recruitment and establishment of a cohort with completed pre‐ and post‐PVI visits (Visit 1 + 2), where PVI resulted in freedom from AF >6 months.

FIGURE 2

IHR hemodynamic responses were compared to their corresponding baseline value prior to IHR and were expressed as percentage change. Data ± SEM. MAP, Mean Arterial Pressure (mmHg) & HR, Heart rate (bpm). Pre and post comparisons for IHR; p < .05.

FIGURE 3

Valsalva phase II response was compared to each corresponding baseline value prior to Valsalva and was expressed as percentage change. Data ± SEM. MAP, Mean Arterial Pressure (mmHg) & HR, Heart rate (bpm). Pre and postcomparisons for Valsalva for Phase II (autonomic phase: II_LATE – II_EARLY; p < .05).

FIGURE 4

LBNP. Forearm Blood Flow (FBF) response to LBNP—20 mmHg and—40 mmHg negative pressure. Expressed as percentage change from baseline. Data ± SEM. Pre and post CV comparisons; p < .05.