CardioExchange Archive

During the Monday afternoon Late-Breaking Clinical Trials session, results of the CASCADE (Clopidogrel After Surgery For Coronary Artery Disease) trial were presented.  The investigators randomized 113 CABG patients to aspirin plus clopidogrel versus aspirin alone.  By 1 year of follow-up, there was no significant difference in the primary endpoint of vein graft intimal area or in the secondary endpoints of vein graft patency or adverse cardiovascular events.

During Monday afternoon’s Late-Breaking Clinical Trials Sessions, results from the Bypassing the Blues trial were reported and simultaneously published in JAMA.  In this study, 453 patients with and without post-CABG depression were followed for 8 months.  Among patients with depression, a telephone-delivered collaborative care intervention improved quality of life, physical functioning, and mood symptoms.

At the Sunday afternoon Late-Breaking Clinical Trial sessions, results from the POPULAR study were presented.  Among 1,069 patients treated with aspirin and clopidogrel at the time of PCI with stent implantation, several platelet reactivity tests were assessed in their ability to predict ischemic and bleeding outcomes.  Only three of six tests (LTA, VerifyNow, and Plateletworks) were able to identify patients at higher risk for the death, MI, stent thrombosis, or stroke at 1 year.  However, none of the tests were able to predict risk of bleeding.

During the Sunday afternoon Late-Breaking Clinical Trials session, the PLATO investigators presented results from a sub-analysis of the 8,430 patients who presented with STEMI in the main trial.  They reported that the reversible oral P2Y12-receptor antagonist, ticagrelor, was associated with reduction in the composite endpoint of MI, stroke, or vascular death when compared to clopidogrel over 1 year.  There was no significant difference in bleeding outcomes.

CardioExchange Editor:  Were the authors surprised by the magnitude of deterioration in EF seen with RVA pacing over the one year follow-up period of the study?  Could this possibly be related to the method of measurement (i.e., 3D echo) or could it be due to inappropriate pacing in patients with sinus node dysfunction?
 
Yu: The magnitude of deterioration in EF was slightly greater than we had initially estimated. As we are looking at small changes in EF and LV end-systolic volume, the use of real-time 3D echo is helpful which is far more accurate than 2D echo.  This might have helped to elucidate the changes in cardiac size and function.  These changes are genuine and occurred equally in both patient groups with high-grade AV block and sinus node dysfunction.    
 
CardioExchange Editor:  We would expect that individuals with baseline lower EF or abnormal LV volumes are more likely to see changes in these same parameters in the setting of a potentially detrimental exposure.  Did you also observe this trend in your study?  In other words, although these individuals may have been fewer in number for a formal analysis, were patients with an EF ~45% more likely to do worse?
 
Yu: This is an interesting question.  However, the primary analysis of PACE was unable to address this hypothesis.  Although it is tempting to suggest that a baseline lower EF might translate to greater a reduction of EF after RVA pacing, this needs to be substantiated by further detailed analyses. 
 
CardioExchange Editor:  This is an important study that builds on prior work in the area of pacing and also makes use of advanced techniques in echocardiography.  Many would agree that ejection fraction is widely assessed in practice, but is still a relatively crude measure.  On the other hand, LV volumes are a nice metric but difficult to measure in practice.  Given their reproducibility in practice, was there a particular reason why LV dimensions (end-diastolic and end-systolic) were not included as endpoints in this analysis? 
 
Yu: Although the use of EF is not a perfect measure of systolic function, it has been the most widely accepted method of analysis.  With the use of 3D echo, the changes in EF can accurately reflect changes in cardiac function as a result of different pacing modalities.  Furthermore, we have captured additional quantitative echocardiographic parameters, such as tissue Doppler imaging for assessment of myocardial systolic velocity, which will be analyzed in due course.  The LV diameter was not used as it is an oversimplified measure of LV size which will not be accurate enough to reflect the actual volumetric changes.  Furthermore, when patients developed systolic dyssynchrony as a result of RVA pacing, the paradoxical septal movement render the measurement of LV diameter even more difficult to interpret.

At the Saturday afternoon Late-Breaking Interventional Clinical Science session, Dr. Helene Eltchaininoff presented early results on outcomes following trans-catheter aortic valve implantations peformed in 244 patients in the French Multicenter Registry.  Overall 30-day mortality was 12.7% and incidence of vascular access related complications was 6.5%.  The outcomes results are comparable to the recently reported experience of a Canadian group that performed aortic valve implantations using trans-arterial and trans-apical approaches.  Providing some context for these data is another AHA presentation by an American group on limitations of wide-spread application of trans-catheter aortic valve implantations.  They found that among 267 patients referred for the procedure, two thirds were deemed unsuitable.  A major reason was mismatch between limited femoral vascular access and need for larger aortic valve size.  They report that improvements in technology may change this trend over time.