Piek, Jan J.

Siebes, Maria

Spaan, Jos A.

Verhoeff, Bart-Jan

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  i2 SUMMIT   
E1864
JACC April 5, 2011
Volume 57, Issue 14
MINIMAL EFFECT OF COLLATERAL FLOW ON CALCULATION OF CORONARY MICROVASCULAR 
RESISTANCE WITH INTERMEDIATE AND NON-CRITICAL CORONARY STENOSES
i2 Poster Contributions
Ernest N. Morial Convention Center, Hall F
Monday, April 04, 2011, 9:30 a.m.-10:45 a.m.
Session Title: Intravascular Diagnostics II
Abstract Category: 3. Intravascular Diagnostics
Session-Poster Board Number: 2509-579
Authors: Maria Siebes, Bart-Jan Verhoeff, Jan J. Piek, Jos A. Spaan, Academic Medical Center, Amsterdam, The Netherlands
Background: Coronary microvascular dysfunction is increasingly recognized as a major contributor to myocardial ischemia and is likely associated 
with an altered hyperemic coronary microvascular resistance, HMR. Selective measurement of HMR in an epicardial artery is influenced by collateral 
flow when a stenosis is present since it induces a pressure gradient between the ipsi- and contra-lateral vessels. Our aim was to assess the 
variability in HMR measurement due to collateral flow at different ranges of stenosis severity as indicated by fractional flow reserve, FFR.
Methods: Intracoronary pressure, Pd, and Doppler flow velocity, v, were measured in 29 patients a total number of 95 times distal to a coronary 
stenosis before and after stepwise percutaneous coronary intervention, PCI. Wedge pressure, Pw, was measured during balloon inflation as an index 
of collateral flow. The following calculations were made: HMR1 = Pd/v, HMR2 = Pa/v * (Pd-Pw)/(Pa-Pw). HMR2 compensates for potential collateral 
flow while HMR1 does not. The relative difference HMRrel = (HMR1 - HMR2)/HMR1 *100% was calculated to indicate the relative error made by 
neglecting collateral flow compensation.
Results: In 17 patients, group A, Pw 25 mmHg (32.3 + 4.5 mmHg). For FFR <= 0.6 HMRrel was about 50% over both groups, with a progressive 
difference between groups A and B at lower FFR. For the diagnostic relevant range of FFR between 0.6 and 0.8, HMRrel was 16.5 ± 10.4% but the 
difference between group A and B was only 12%. For FFR >= 0.8 the overall mean difference was 4.4 ± 3.4% and the difference between the two 
groups not more than 2%. For FFR >= 0.8 both microvascular indices varied between a minimum of 0.9 and maximum of 3 mm Hg · sec/cm.
Conclusions: Coronary hyperemic microvascular resistance is only weakly affected by coronary collateral flow contribution in the presence of non-
critical or intermediate coronary stenosis. HMR can therefore be assessed by the ratio of Pd over v before and after a successful PCI.


MINIMAL EFFECT OF COLLATERAL FLOW ON CALCULATION OF CORONARY MICROVASCULAR RESISTANCE WITH INTERMEDIATE AND NON-CRITICAL CORONARY STENOSES 

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MINIMAL EFFECT OF COLLATERAL FLOW ON CALCULATION OF CORONARY MICROVASCULAR RESISTANCE WITH INTERMEDIATE AND NON-CRITICAL CORONARY STENOSES

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