Luke C. McSpadden

Multipoint left ventricular pacing improves acute hemodynamic response assessed with pressure-volume loops in cardiac resynchronization therapy patients

BACKGROUND Conventional cardiac resynchronization therapy (CRT) improves acute cardiac hemodynamics. OBJECTIVE To investigate if CRT with multipoint left ventricular (LV) pacing in a single coronary sinus branch (MultiPoint Pacing [MPP], St Jude Medical, Sylmar, CA) can offer further hemodynamic benefits to patients. METHODS Forty-four consecutive patients (80% men, New York Heart Association III, end-systolic volume 180 ± 77 mL, ejection fraction 27% ± 6%, and QRS duration 152 ± 17 ms) receiving a CRT device implant (Unify Quadra MP or Quadra Assura MP and Quartet LV lead, St Jude Medical) underwent intraoperative assessment of LV hemodynamics by using a pressure-volume loop system (Inca, CD Leycom). A pacing protocol was performed, including 9 biventricular pacing interventions with conventional CRT (CONV) using distal and proximal LV electrodes and various MPP configurations. Each pacing intervention was performed twice in randomized order with right ventricular pacing (BASELINE) repeated after every intervention. RESULTS Evaluable recordings were obtained in 42 patients. Relative to BASELINE, the best MPP intervention significantly increased the rate of pressure change (dP/dtmax; 15.9% ± 10.0% vs 13.5% ± 8.8%; P < .001), stroke work (27.2% ± 42.5% vs 19.4% ± 32.2%; P = .018), stroke volume (10.4% ± 22.5% vs 4.1% ± 13.1%; P = .003), and ejection fraction (10.5% ± 20.9% vs 5.3% ± 13.2%; P = .003) as compared with the best CONV intervention. Moreover, the best MPP intervention improved acute diastolic function, significantly decreasing -dP/dtmin (-13.5% ± 10.2% vs -10.6% ± 6.8%; P = .011), relaxation time constant (-7.5% ± 9.0% vs -4.8% ± 7.2%; P = .012), and end-diastolic pressure (-18.2% ± 22.4% vs -8.7% ± 21.4%; P < .001) as compared with the best CONV intervention. CONCLUSIONS CRT with MPP can significantly improve acute LV hemodynamic parameters assessed with pressure-volume loop measurements as compared with CONV.

Improving cardiac resynchronization therapy response with multipoint left ventricular pacing: Twelve-month follow-up study

BACKGROUND Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint™ Pacing [MPP], St. Jude Medical) improves acute LV function and LV reverse remodeling at 3 months. OBJECTIVE The purpose of this study was to test the hypothesis that MPP can also improve LV function at 12 months. METHODS Consecutive patients receiving a CRT implant (Unify Quadra MP™ or Quadra Assura MP™ CRT-D and Quartet™ LV lead, St. Jude Medical) were randomized to receive pressure-volume (PV) loop optimized biventricular pacing with either conventional cardiac resynchronization therapy (CONV) or MPP. CRT response was defined by a reduction in end-systolic volume (ESV) ≥15% relative to BASELINE as determined by a blinded observer and alive status. RESULTS Forty-four patients (New York Heart Association class III, ejection fraction [EF] 29% ± 6%, QRS 152 ± 17 ms) were enrolled and randomized to either CONV (N = 22) or MPP (N = 22). During the observation period, 2 patients died of noncardiac causes and 2 patients were lost to follow-up. After 12 months, 12 of 21 patients (57%) in the CONV group and 16 of 21 patients (76%) in the MPP group were classified as CRT responders (P = .33). ESV reduction and EF increase relative to BASELINE were significantly greater with MPP than with CONV (ESV: median -25%, interquartile range [IQR] [-39% to -20%] vs median -18%, IQR [-25% to -2%], P = .03; EF: median +15%, IQR [8% to 20%] vs median +5%, IQR [-1% to 8%], P <.001). CONCLUSION Sustaining the trend observed 3 months postimplant, PV loop-guided multipoint LV pacing resulted in greater LV reverse remodeling and increased LV function at 12 months compared to PV loop-guided conventional CRT.

Multipoint Left Ventricular Pacing in a Single Coronary Sinus Branch Improves Mid‐Term Echocardiographic and Clinical Response to Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing in a single coronary sinus branch improves acute LV function. We hypothesized that multipoint pacing (MPP) can improve midterm echocardiographic and clinical response compared with conventional CRT.

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents

Aims The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT). Methods and Results A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355). Bipolar and tripolar lead configurations were modelled by systematic elimination of two and one electrode(s), respectively, from the Quartet lead. The Quartet lead with its four pacing electrodes exhibited the greatest number of pacing vectors per patient when compared with the best bipolar and the best tripolar modelled equivalents. Similarly, the Quartet lead provided the highest spatial coverage in terms of the distance between two furthest viable pacing cathodes when compared with the best bipolar and the best tripolar configurations (P < 0.05). Among the three modelled bipolar configurations, the lead configuration with the two most distal electrodes resulted in the highest number of viable pacing vectors. Among the four modelled tripolar configurations, elimination of the second proximal electrode (M3) resulted in the highest number of viable pacing options per patient. There were no significant differences observed between pre-discharge and first follow-up analyses. Conclusion The Quartet lead with its four electrodes and the capability to pace from four anatomical locations provided the highest number of viable pacing vectors at pre-discharge and first follow-up visits, providing more flexibility in device programming and enabling continuation of CRT in more patients when compared with bipolar and tripolar equivalents.

Predictive value of unipolar and bipolar electrograms in idiopathic outflow tract ventricular arrhythmia mapping and ablation

Radiofrequency catheter ablation is an effective therapy for focal idiopathic outflow tract ventricular arrhythmia (OTVA). However, visual inspection of the unipolar electrogram (EGM) QS morphology is subjective with a poor specificity for predicting successful ablation sites. This study aims to evaluate the predictive value of unipolar and bipolar EGMs in OTVA mapping and ablation.