Myocardial Revascularization

Fausto J Pinto, MD, University of Lisbon, Lisbon, Portugal, reviewed the 2010 Guidelines for Myocardial Revascularization as issued by the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) [Eur Heart J 2010; Eur J CardioThoracic Surg 2010].

One of the highlights of the new guidelines is the recommendation on the use of risk stratification scores for patients who are candidates for percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG; Table 1).

For PCI the SYNTAX score is preferred to quantify the complexity of coronary artery disease (CAD) but additional testing is needed [Class IIa; Level of Evidence B]

For CABG either the EuroSCORE or STS score can be used; however, the STS score undergoes periodic adjustment which makes longitudinal comparisons difficult [Class I; Level of Evidence B]

The new guidelines also address the issue of informed consent in cardiac surgery and PCI. Patients too often have partial/poor understanding of the risks, benefits, and alternatives yet those patients who play an active role in decision making have better outcomes. Thus, the new guidelines recommend that patients be adequately informed about the potential benefits and short- and long-term risks of revascularization. A sample patient information document is available in the Appendix in the online version of the guidelines.

The 2010 Guidelines also recommend multidisciplinary decision making by a consolidated Heart Team in each institution. Collaboration and discussion between the clinical noninterventional cardiologist, the interventional cardiologist, and the cardiac surgeon are strongly recommended as is the inclusion of other medical specialists (ie, nephrologists, diabetologists, neurologists, geriatricians) when treating patients with complex CAD and/or multiple associated co-morbidities.

While the guidelines recognize that ad hoc PCI is convenient for the patient, associated with fewer access site complications, and is often cost effective, there is also a recognition that it is not desirable for all patients and should not be applied as the default approach. Thus, the potential indications for ad hoc PCI and revascularization at an interval are defined (Table 2).

CAD can be treated with optimal medical therapy (OMT) alone or combined with revascularization using PCI or CABG, depending on symptomatic, functional, and anatomic complexity. Treatment decisions must consider the appropriateness of the revascularization and the relative merits of PCI and CABG for different types of CAD. The guidelines recognize the increasing use of Fractional Flow Reserve (FFR) measurements to identify functionally more important lesions. Revascularization can be justified on either prognostic or symptomatic grounds (Table 3). Significant left main stenosis and significant proximal left anterior descending artery disease, especially in the presence of multivessel CAD, are strong indications for revascularization. While the choice of whether to use PCI or CABG must consider individual patient preferences and clinical characteristics, the guidelines provide some recommendations (Table 4).

New recommendations with respect to revascularization in non-ST-segment elevation acute coronary syndrome (NSTE-ACS) recognize the importance of a patient's GRACE score in determining the timing of the intervention. For PCI in ST-segment elevation myocardial infarction (STEMI) the new guidelines recommend that patients be transferred to a primary PCI center if PCI is possible within 2 hours and that rescue PCI should be considered in patients who have failed fibrinolysis.

Both prasugrel and ticagrelor have been added to the approved list of antithrombotic treatment options for myocardial revascularization [both Class I; Level of Evidence B]. Specific recommendations have been added for myocardial revascularization in diabetic patients and in patients with chronic heart failure. The importance of OMT and lifestyle changes is emphasized in all patients with CAD.

Cardiac Resynchronization Therapy (CRT)

Over the last decade there has been much progress in CRT including improved lead delivery systems, improved programmability, and higher success rates of endocardial left ventricular (LV) lead placement. There is also a wealth of evidence from clinical trials showing that CRT improves quality-of-life, NYHA class, and performance on the 6-Minute Walk Test. CRT achieves its effects by optimizing atrioventricular (AV) delay and synchronizing the left and right ventricles. Optimized AV delay decreases mitral regurgitation, increases diastolic filling time, and improves LV dP/dt while synchronization of the left and right ventricles improves interventricular synchrony, reduces paradoxical septal wall motion, improves LV regional wall motion, lowers end-systolic volumes, and improves LV dP/dt

Mohammad Shenasa, MD, O'Connor Hospital, San Jose, California, USA, discussed the current Guidelines and Indications for CRT in patients with HF (Table 5) and reviewed the results of several trials evaluating CRT in HF.

Although the majority of the evidence for CRT in HF comes from studies in patients with NYHA class III or IV, HF several trials have examined the value of CRT alone or in combination with an implantable cardioverter-defibrillator (CRT-D) in patients with mild (class I or II; Table 5) HF. Dr. Shenasa discussed several of these trials. Among these were the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) and Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) trials.

The objective of the REVERSE study was to determine if CRT could prevent or slow HF progression in patients with asymptomatic LV dysfunction or mildly symptomatic disease. The REVERSE study did not meet its primary endpoint (a composite response comparing the proportion of patients with worsened disease in the CRT-on vs CRT-off groups); however, among the subgroups of patients who improved, remained the same, or worsened, patients in the CRT-on group were significantly more likely to have improved over the course of 12 months (p<0.0001) [Linde C et al. J Am Coll Cardiol 2008].

In the MADIT-CRT trial patients with ischemic or nonischemic cardiomyopathy, an ejection fraction of ≤30%, a QRS duration ≥130 m/sec, and NYHA class I or II symptoms were randomly assigned to receive CRT-D or an ICD alone. CRT-D decreased the risk of HF events. In addition, CRT was associated with a significant reduction in LV volumes and improvement in ejection fraction. These findings suggest that CRT may be used as an early management of heart failure with LV dysynchrony. However 12 patients need to be treated in order to save 1 heart failure patient. [Jessup M. N Engl J Med 2009] no significant difference between the two groups in the overall risk of death. Serious adverse events were infrequent [Moss AN et al. N Engl J Med 2009].

Tang and colleagues [N Engl J Med 2010] have recently reported results from the Resynchronization/Defibrillation for Ambulatory Heart Failure Trial (RAFT) showing that among patients with NYHA class II or III heart failure, a wide QRS complex, and LV systolic dysfunction, the addition of CRT-D reduces the rates of death and hospitalization for HF, although the improvement was accompanied by more adverse events.

Despite these studies, controversy remains concerning the use of CRT in patients with NYHA I-II HF [Reynolds CR et al. Circulation 2011; Tang WHW & Francis GS. Circulation 2011].