A systematic approach to designing reliable VV optimization methodology: Assessment of internal validity of echocardiographic, electrocardiographic and haemodynamic optimization of cardiac resynchronization therapy

• Published in: International journal of cardiology Vol. 167; no. 3; pp. 954 - 964
• Main Authors: Kyriacou, Andreas, Li Kam Wa, Matthew E, Pabari, Punam A, Unsworth, Beth, Baruah, Resham, Willson, Keith, Peters, Nicholas S, Kanagaratnam, Prapa, Hughes, Alun D, Mayet, Jamil, Whinnett, Zachary I, Francis, Darrel P
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 10-08-2013; Elsevier
• Subjects: Aged; Aged, 80 and over; Biological and medical sciences; Biventricular pacemakers; Cardiac Pacing, Artificial - methods; Cardiac Pacing, Artificial - standards; Cardiac Resynchronization Therapy - methods; Cardiac Resynchronization Therapy - standards; Cardiology. Vascular system; Cardiovascular; Cardiovascular system; Cohort Studies; Echocardiography; Echocardiography - methods; Echocardiography - standards; Electrocardiography; Electrocardiography - methods; Electrocardiography - standards; Female; Heart; Hemodynamics - physiology; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Pressure; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Research Design - standards; Ultrasonic investigative techniques; Electrocardiography; Biventricular pacemakers; Echocardiography; Pressure; Sonography; Cardiac resynchronization; Methodology; Internal; Instrumentation therapy; Cardiovascular disease; Optimization; Electrodiagnosis; Instrumental stimulation; Validity; Pacemaker; Surgical approach; Hemodynamics; Cardiology
• ISSN: 0167-5273; 1874-1754
• DOI: 10.1016/j.ijcard.2012.03.086

Abstract Background In atrial fibrillation (AF), VV optimization of biventricular pacemakers can be examined in isolation. We used this approach to evaluate internal validity of three VV optimization methods by three criteria. Methods and results Twenty patients (16 men, age 75 ± 7) in AF were optimized, at two paced heart rates, by LVOT VTI (flow), non-invasive arterial pressure, and ECG (minimizing QRS duration). Each optimization method was evaluated for: singularity (unique peak of function), reproducibility of optimum, and biological plausibility of the distribution of optima. The reproducibility (standard deviation of the difference, SDD) of the optimal VV delay was 10 ms for pressure, versus 8 ms (p = ns) for QRS and 34 ms (p < 0.01) for flow. Singularity of optimum was 85% for pressure, 63% for ECG and 45% for flow (Chi2 = 10.9, p < 0.005). The distribution of pressure optima was biologically plausible, with 80% LV pre-excited (p = 0.007). The distributions of ECG (55% LV pre-excitation) and flow (45% LV pre-excitation) optima were no different to random (p = ns). The pressure-derived optimal VV delay is unaffected by the paced rate: SDD between slow and fast heart rate is 9 ms, no different from the reproducibility SDD at both heart rates. Conclusions Using non-invasive arterial pressure, VV delay optimization by parabolic fitting is achievable with good precision, satisfying all 3 criteria of internal validity. VV optimum is unaffected by heart rate. Neither QRS minimization nor LVOT VTI satisfy all validity criteria, and therefore seem weaker candidate modalities for VV optimization. AF, unlinking interventricular from atrioventricular delay, uniquely exposes resynchronization concepts to experimental scrutiny.