TY - JOUR
T1 - When is an optimization not an optimization? Evaluation of clinical implications of information content (signal-to-noise ratio) in optimization of cardiac resynchronization therapy, and how to measure and maximize it
AU - Pabari, Punam A.
AU - Willson, Keith
AU - Stegemann, Berthold
AU - van Geldorp, Irene E.
AU - Kyriacou, Andreas
AU - Moraldo, Michela
AU - Mayet, Jamil
AU - Hughes, Alun D.
AU - Francis, Darrel P.
PY - 2011/5
Y1 - 2011/5
N2 - Impact of variability in the measured parameter is rarely considered in designing clinical protocols for optimization of atrioventricular (AV) or interventricular (VV) delay of cardiac resynchronization therapy (CRT). In this article, we approach this question quantitatively using mathematical simulation in which the true optimum is known and examine practical implications using some real measurements. We calculated the performance of any optimization process that selects the pacing setting which maximizes an underlying signal, such as flow or pressure, in the presence of overlying random variability (noise). If signal and noise are of equal size, for a 5-choice optimization (60, 100, 140, 180, 220 ms), replicate AV delay optima are rarely identical but rather scattered with a standard deviation of 45 ms. This scatter was overwhelmingly determined (rho = -0.975, P <0.001) by Information Content, Signal/Signal+Noise, an expression of signal-to-noise ratio. Averaging multiple replicates improves information content. In real clinical data, at resting, heart rate information content is often only 0.2-0.3; elevated pacing rates can raise information content above 0.5. Low information content (e.
AB - Impact of variability in the measured parameter is rarely considered in designing clinical protocols for optimization of atrioventricular (AV) or interventricular (VV) delay of cardiac resynchronization therapy (CRT). In this article, we approach this question quantitatively using mathematical simulation in which the true optimum is known and examine practical implications using some real measurements. We calculated the performance of any optimization process that selects the pacing setting which maximizes an underlying signal, such as flow or pressure, in the presence of overlying random variability (noise). If signal and noise are of equal size, for a 5-choice optimization (60, 100, 140, 180, 220 ms), replicate AV delay optima are rarely identical but rather scattered with a standard deviation of 45 ms. This scatter was overwhelmingly determined (rho = -0.975, P <0.001) by Information Content, Signal/Signal+Noise, an expression of signal-to-noise ratio. Averaging multiple replicates improves information content. In real clinical data, at resting, heart rate information content is often only 0.2-0.3; elevated pacing rates can raise information content above 0.5. Low information content (e.
KW - Cardiac resynchronization therapy
KW - Biventricular pacemaker
KW - Optimization
KW - Echocardiography
KW - Velocity-time integral
KW - Blood pressure
U2 - 10.1007/s10741-010-9203-5
DO - 10.1007/s10741-010-9203-5
M3 - Article
C2 - 21110226
SN - 1382-4147
VL - 16
SP - 277
EP - 290
JO - Heart Failure Reviews
JF - Heart Failure Reviews
IS - 3
ER -