Complete Revascularization with PCI in Patients with LV Dysfunction
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco. Dr. Boyle reports on financial relationships relevant to this field of study.
Source: Kirschbaum SW, et al. Complete percutaneous revascularization for multivessel disease in patients with impaired left ventricular function: Pre- and post-procedural evaluation by cardiac magnetic resonance imaging. J Am Coll Cardiol Interv. 2010;3:392-400.
Ischemic cardiomyopathy remains a frequent cause of heart failure. Management of patients with coronary artery disease with LV dysfunction has traditionally been achieved with coronary artery bypass graft surgery (CABG). More recently, percutaneous coronary intervention (PCI) has shown similar results to CABG in patients with multi-vessel coronary artery disease. However, the role of PCI in patients with multi-vessel disease and LV dysfunction remains to be defined. Key considerations in the decision-making process of whether or not to revascularize a patient with LV dysfunction include whether or not the LV dysfunction is due to ischemia and whether this will improve with revascularization. All methods of assessing myocardial viability have limitations. Therefore, Kirschbaum and colleagues performed a prospective study using cardiac MRI to determine the effects of PCI on LV function in patients with multi-vessel disease. They focused on comparing the effects of complete vs. partial revascularization.
Patients referred for PCI who had LV wall-motion abnormalities were prospectively enrolled in this study and underwent MRI with dobutamine stress and gadolinium-delayed enhancement. Inclusion criteria included significant stenosis (> 50%) in at least two vessels, sinus rhythm, and a wall-motion abnormality. Exclusion criteria were recent myocardial infarction (MI), unstable angina, and contraindications to MRI. Seventy-seven patients completed their first MRI, and 71 underwent follow-up MRI at 7 ± 1 months after PCI. Patients were considered to have had complete revascularization if all lesions greater than 50% were treated (n = 34), incomplete revascularization if one but not all lesions were treated (n = 22), and unsuccessful revascularization if no lesions were treated (n = 15). Baseline characteristics were similar between these groups. Mean age was 62 years, 64%-82% were male, and baseline LVEF was 46%-49%. The only differences between the groups were that chronic total occlusions (CTOs) were more prevalent in the incomplete and unsuccessful revascularization groups than in the complete group (86%, 67%, and 59%, respectively; p = 0.04), and the LAD was less likely to be involved in the unsuccessful group (25%) than the other groups (each 38%; p = 0.04). Patients had an average of 2.4 significant lesions. All patients received drug-eluting stents.
Results: In patients receiving complete revascularization, LVEF improved by 4% ± 5% (p < 0.0001), end-systolic volume index (ESVI) improved by 5 ± 8 mL/m2 (p < 0.001), and cardiac output improved by 0.5 ± 1.2 L/min (p = 0.02). Patients with incomplete or unsuccessful revascularization had no change in LVEF, ESVI, or cardiac output. The improvement in LVEF correlated with dysfunctional but viable segments assessed by two MRI parameters: < 25% transmural infarction and contractile reserve > 7%. The sensitivity and specificity for predicting improvement in global LV function for transmural infarction < 25% were 70% and 77%, respectively. For contractile reserve, they were 100% and 75%, respectively.
Peri-procedural myocardial damage was common, occurring in 10/34 patients with complete revascularization, and this translated into three patients with newly detectable scar by delayed-enhancement MRI. However, this did not prevent improvement in overall LV function and did not significantly change overall infarct scar size. The authors conclude that complete revascularization for multi-vessel coronary artery disease improves EF, whereas EF did not change in patients after incomplete or unsuccessful revascularization. Improvement in EF can be predicted by performing cardiac MRI before PCI.
Commentary
Not surprisingly, Kirschbaum et al showed that dysfunctional but viable segments of myocardium improve with revascularization, and that MRI parameters can predict improvement. However, the predictive value of the tests is imperfect, as with other tests of viability before revascularization. The predictive power of MRI in this study is similar in magnitude to other modalities of assessing viability, such as MRI or dobutamine echo. This study is encouraging that complete revascularization by PCI can improve ischemic cardiac dysfunction, just as has been shown for CABG in the past, particularly as some advocate only revascularizing the "culprit" lesion and only for anginal symptoms. However, several issues with this study require discussion. Firstly, this was an observational study, so no conclusions should be drawn on whether using these MRI parameters to change management will result in better outcomes. Secondly, there is inherent selection bias when including only patients who are already referred for PCI. Thirdly, the authors chose to define all coronary artery lesions greater than 50% as significant. Whether this is the appropriate cut-off, or whether functional criteria would have been better ways to define significant, remains to be tested in future clinical trials. However, the authors have taken a step toward tackling the issue of complete vs. incomplete revascularization with PCI in patients with LV dysfunction. Just as CABG usually aims for complete revascularization rather than just "culprit" lesion revascularization, perhaps PCI should also have the same aim. This remains to be studied in future randomized, controlled trials.
Ischemic cardiomyopathy remains a frequent cause of heart failure. Management of patients with coronary artery disease with LV dysfunction has traditionally been achieved with coronary artery bypass graft surgery (CABG). More recently, percutaneous coronary intervention (PCI) has shown similar results to CABG in patients with multi-vessel coronary artery disease.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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