Two Conduction-System Pacing RCTs Give Conflicting Results

Why It Matters

These divergent outcomes affect guideline recommendations for CRT, reinforcing BiV pacing as the default while highlighting the need for skilled operators before CSP can be widely adopted.

Key Takeaways

• HeartSync-LBBP showed lower death/HF hospitalization vs BiV.
• PhysioSync-HF failed non-inferiority, higher mortality with CSP.
• Operator experience strongly influenced outcomes in both trials.
• CSP benefits limited to expert centers; BiV remains first-line.
• Ongoing large RCTs needed to define CSP role.

Pulse Analysis

Cardiac resynchronization therapy has long relied on biventricular pacing, a technique refined over two decades and embedded in major heart‑failure guidelines. Conduction‑system pacing, which directly engages the heart’s native electrical pathways, promises tighter electrical synchrony and potentially superior remodeling. The recent HeartSync‑LBBP and PhysioSync‑HF trials represent the largest head‑to‑head comparisons of these strategies, offering a rare glimpse into real‑world efficacy and safety across different health‑care systems.

The Chinese HeartSync‑LBBP trial demonstrated a striking 74% relative reduction in the composite of death or heart‑failure hospitalization over a median 36‑month follow‑up, driven by markedly fewer hospital admissions and higher rates of super‑response. In contrast, the Brazilian PhysioSync‑HF study reported higher mortality and failed to achieve non‑inferiority, with a notable proportion of implants performed by operators lacking extensive CSP experience. This disparity underscores how procedural expertise, patient selection criteria, and consistent left‑bundle capture critically shape outcomes. Even subtle variations in lead positioning can shift a therapy from benefit to harm, especially in patients with advanced cardiomyopathy.

For clinicians and device manufacturers, the take‑away is clear: CSP cannot yet supplant BiV pacing as the universal first‑line CRT approach. Until larger, adequately powered RCTs confirm survival and quality‑of‑life advantages, guidelines will likely continue to favor biventricular systems, reserving CSP for high‑volume centers with proven proficiency. Ongoing trials slated for release in the next few years will be pivotal in determining whether CSP can earn a broader role in the heart‑failure market and justify investment in specialized training and equipment.