PROSPECTIVE VALIDATION OF AUTOMATED RIGHT VENTRICULAR OVERDRIVE PACING FOR SIMPLIFIED DIFFERENTIAL DIAGNOSIS OF SUPRAVENTRICULAR TACHYCARDIAS IN CHILDREN AND ADULTS
Introduction: Right ventricular overdrive pacing (RVOP) with an evaluation of transition zone (TZ) has been shown to have good diagnostic value independent of entrainment success for differentiating orthodromic reciprocating tachycardia (OAVRT) from typical and atypical atrioventricular nodal reentrant tachycardia (AVNRT) and atrial tachycardia (AT). There is however limited information on prospective evaluation of this method while using simplified 2-catheter approach with an automatic RVOP from right ventricular inflow (RVIT) and outflow tract (RVOT).
Methods: Entrainment of the tachycardia was attempted by 10 pacing pulses from the RVOT/RVIT at a pacing cycle length (PCL) 20-40 ms shorter than the tachycardia cycle length (TCL). Automatically sensed to QRS complex 10-beat pacing trains were applied using EP-Tracer system (CardioTek, Maastricht, the Netherlands). TZ during RVOP includes progressively fused QRS complexes and the first paced complex with a stable QRS morphology based on analysis of the 12-lead ECG. The fixed AA interval (AAfix = AA#15 ms), the fixed stimulus-atrial intervals (SAfix= SA#10 ms) were measured.
Results: 103 patients (46±16 years, range:4-80) with 105 AVNRT/OAVRT/AT were prospectively recruited. Using the standardized protocol and settings successful RVOP was achieved after a mean 1.3±0.8 attempts from RVIT and 1.7±1.0 attempts from RVOT (p<0.002). SAfix was observed within the TZ in all patients with OAVRT (100% vs 100%, p=NS, from RVIT and RVOT respectively) and only in 2% and 1% patient with AVNRT/AT. In OAVRT SAfix occurred significantly earlier than in AVNRT/AT (-1.0±0.9 vs 1.7±0.9 the last QRS of the TZ, p<0.001) Both responses (AAfix and SAfix) within the TZ after RVOP were observed in 30/31 OAVRT (either from RVOT or RVIT) and in only 1/84 AVNRT/AT.
Conclusions: Using 2-catheter approach and automatic RVOP either from RVIT or RVOT may simplify procedure and enable rapid and accurate distinction of OAVRT from AVNRT and AT in children and adults.