Rick Schreurs

51 Cardiac pacing in first degree AV-block Table 3. Hemodynamic and electrocardiographic data in patients paced at various paced AV-delays (% of intrinsic PR-interval – 30ms) AV-delay (=PR-30ms) 25% 50% 75% 100% AAI BiV pacing BL AV-delay (ms) 70±14* 137±30* 203±40* 270±51* 300±61 QRS duration (ms) 147±24*† 149±22*† 142±22† 129±29 128±25 LVP max (mmHg) 110±22* 115±23 117±24 117±25 118±25 Stroke work (mL*mmHg) 4993±2041† 5605±2263*† 5726±2369* 5273±2128* 4792±1992 LV dP/dt max (mmHg/s) 896±164† 935±153† 965±162† 971±165* 927±166 LV EDP (mmHg) 11±5 13±6* 13±8* 11±7 11±6 LV EDV (mL) 208±55 215±56 215±59 213±55 215±56 Stroke volume (ml) 53±19† 58±20*† 59±21* 53±18* 48±16 Diastolic forward flow (mL/beat) 65±22† 69±23*† 68±22* 66±21* 61±21 MR fraction (%) 9±9* 6±6* 9±9* 12±9* 18±11 Diastolic filling time (ms) 434±104* 432±104 429±111 415±93 417±87 RV pacing BL AV-delay (ms) 70±14 137±30 203±40 270±51 300±61 QRS duration (ms) 175±20* 173±20* 165±22* 143±25 128±25 LVP max (mmHg) 109±19* 115±22 118±24 120±24 118±25 Stroke work (mL*mmHg) 3885±1844* 4455±2055 4811±2254 4904±2090 4792±1992 LV dP/dt max (mmHg/s) 801±145* 845±144* 896±163 951±148 927±166 LV EDP (mmHg) 11±7 12±7 13±7* 11±6 11±6 LV EDV (mL) 213±51 220±55 222±56 219±51 215±56 Stroke volume (ml) 42±17 46±19 48±19 48±18 48±16 Diastolic forward flow (mL/beat) 55±22 59±23 61±24 62±24 61±21 MR fraction (%) 13±12 11±9 14±10 17±10 18±11 Diastolic filling time (ms) 416±99 409±91 411±95 414±101 417±87 Results are presented as mean±SD (n=22). BiV: biventricular, AV: atrioventricular, LV: left ventricular, EDP: end diastolic pressure, EDV: end diastolic volume, MR: mitral regurgitation, RV: right ventricular. * indicates P<0.05 compared to baseline, † indicates P<0.05 compared to RV pacing with corresponding AV-delay DISCUSSION The presented combination of computational, experimental and clinical proof-of-principle studies provides strong evidence that restoration of AV-coupling by BiV pacing results in significant hemodynamic benefit in hearts with AV dromotropathy (evidenced by a prolonged PR-interval). This benefit is caused by 1) increased ventricular filling, established by a larger forward flow across the mitral valve and less late-diastolic MR, but 2) is 3