Magnetic resonance imaging versus Doppler guide wire in the assessment of coronary flow reserve in patients with coronary artery disease

Background: Coronary flow velocity reserve (CFVR), defined as the ratio of maximal hyperaemic to baseline flow velocity, has been validated as a marker of physiological significance of a coronary lesion. Clinically, this parameter is measured invasively during X-ray angiography using the Doppler guide wire. With magnetic resonance (MR) imaging it is possible to quantify CFVR non-invasively. Design: The purpose of the study was to compare CFVR, acquired with MR imaging and the Doppler guide wire in patients with coronary artery disease. Methods: Twenty-two patients suffering from one- or two-vessel coronary artery disease as derived from diagnostic X-ray coronary angiography were included. Coronary flow velocity reserve was measured at baseline and during maximal hyperaemia, obtained by intravenous administration of adenosine using MR phase contrast velocity quantification. Within 2 weeks CFVR was measured invasively with a Doppler guide wire. Results: In 26 coronary arteries CFVR was acquired with both techniques. Mean CFVR in the stenosed and healthy reference arteries was 1.5 ± 0.7 and 2.7 ± 1.0 (P < 0.01) respectively for MR measurements and 1.9 ± 0.7 and 3.1 ± 0.6 (P < 0.01) respectively for Doppler measurements. Bland-Altman analysis revealed a non-significant mean difference between the two techniques of 0.4 ± 1.2. Conclusion: In a selected group of stable patients with coronary artery disease MR flow velocity quantification provides non-invasive data equivalent to the invasive Doppler guide wire data. Variability in both the MR and Doppler ultrasound measurement resulted in a significant scatter of data without systematic difference

Quantitative comparison of 2D and 3D circumferential strain using MRI tagging in normal and LBBB hearts

The response to cardiac resynchronization therapy (CRT), which is applied to patients with heart failure (HF) and left bundle-branch block (LBBB), can be predicted from the mechanical dyssynchrony measured on circumferential strain. Circumferential strain can be assessed by either 2D or 3D strain analysis. In this study was evaluated the difference between 2D and 3D circumferential strain using MR tagging with high temporal resolution (14 ms). Six healthy volunteers and five patients with LBBB were evaluated. We compared the 2D and 3D circumferential strains by computing the mechanical dyssynchrony and the cross correlation (r) between 2D and 3D strain curves, and by quantifying the differences in peak circumferential shortening, time to onset, and time to peak of shortening. The obtained maximum r2 values were 0.97 ± 0.03 and 0.87 ± 0.16 for the healthy and LBBB populations, respectively, and thus showed a good similarity between 2D and 3D strain curves. No significant difference was observed between 2D and 3D in time to onset, time to peak, or peak circumferential shortening. Thus, to measure dyssynchrony, 2D strain analysis will suffice. Since 2D analysis is easier to implement than 3D analysis, this finding brings the application of MRI tagging and strain analysis closer to the clinical routine

High dose adenosine for suboptimal myocardial reperfusion after primary PCI: A randomized placebo-controlled pilot study

Objectives: This study was designed to investigate the influence of high dose intracoronary adenosine on persistent ST-segment elevation after primary percutaneous coronary intervention (PCI). Background: After successful PCI for acute myocardial infarction 40-50% of patients show persistent ST-segment elevation indicating suboptimal myocardial reperfusion. Adenosine has been studied to ameliorate reperfusion and is frequently used in a variety of doses, but there are no prospective studies to support its use for treatment of suboptimal reperfusion. Methods: We conducted a blinded, randomized, and placebo-controlled study with high dose intracoronary adenosine in 51 patients with 70%) STRes compared with placebo (33% versus 9%, P <0.05). Mean STRes was higher after adenosine (35.4% versus 23.0%, P <0.05). In addition, TIMI frame count was significant lower (15.7 versus 30.2, P <0.005), Myocardial Blush Grade was higher (2.7 versus 2.0, P <0.05) and resistance index was lower in the adenosine group (0.70 versus 1.31 mm Hg per ml/min, P <0.005). Conclusions: Intracoronary adenosine accelerates recovery of microvascular perfusion in case of persistent ST segment elevation after primary PCI. (c) 2008 Wiley-Liss, Inc