Top Advances in Cardiovascular Surgery in 2009

Updated:Jun 4,2014

Top Advances in Cardiovascular Surgery in 2009

Disclosure: Ikaria, significant; Capstone Therapeutics, significant; Pfizer (pharmaceutical consultant for Celebrex/Bextra litigation), significant; Cubist (DSMB), modest; Novo Nordisk (steering committee), modest.
Pub Date: Friday, January 15, 2010
Author: Frank W. Sellke, MD, FAHA

Article Text

What constitutes a major advance in any field is debatable, but there have been several contributions in 2009 that require us to reassess how we surgically treat our patients with cardiovascular disease.

The first study by Shroyer et al., as part of a Randomized On/Off Bypass (ROOBY) study group, examined "On-Pump versus Off-Pump, Coronary Artery Bypass Surgery."[1] This long awaited study from the U.S. Department of Veterans Affairs compared two methods used to surgically revascularize the heart, namely coronary artery bypass graft (CABG) with or without the use of the heart lung machine. Two thousand two hundred and three patients from Veterans Affairs medical centers scheduled to undergo CABG were randomized to have their operation either with (on-pump) or without (off-pump) the heart lung machine. Although there was no difference between off-pump and on-pump CABG in the 30-day composite outcome of death, repeat revascularization, or nonfatal myocardial infarction (MI), the 1-year composite outcome was less favorable in the off-pump than the on-pump CABG group by a small but significant degree. The proportion of patients with fewer bypass grafts completed compared with those planned was also higher in the off-pump group compared with the on-pump CABG group, suggesting less completeness of revascularization with the off-pump method. There was a 5% difference in graft patency favoring the on-pump group. Interestingly, there were no treatment-based differences in neuropsychiatric outcomes or short-term use of hospital resources. This is contradictory to several initial studies but consistent with later trials comparing the two methods. The authors concluded that at 1 year, patients undergoing off-pump coronary bypass grafting had worse outcomes compared with those undergoing on-pump coronary bypass surgery. Few topics in cardiac surgery have received more attention than the controversy regarding the relative benefits of on-pump and off-pump CABG. Although initial studies suggested that off-pump CABG may provide improved outcome, less neurocognitive dysfunction, and shorter length of stay, this and other recent studies have suggested that the two approaches lead to similar outcomes or that the on-pump approach may hold a slight advantage with regard to graft patency and death, nonfatal MI, and the need for subsequent revascularization. There may be some limited instances for which one method or the other may be superior, but for the vast majority of patients, little difference is apparent.

No one can dispute that the incidence of saphenous vein harvesting complications has been markedly reduced with the advent of endoscopic techniques. Currently, endoscopic vein harvesting is widely used, but the long-term consequences have not been known. Some have suspected that as a result of increased trauma due to endoscopic harvesting, there may be diminished long-term graft patency. In this study [2], Lopes et al. studied the outcomes of CABG in patients who underwent endoscopic saphenous vein harvesting compared with those who underwent open harvesting under direct vision. The rate of vein graft failure at 12 to 18 months was significantly higher for those undergoing endoscopic vein harvesting compared with those who underwent open harvesting: 47% versus 38%. At 3 years, endoscopic harvesting is associated with higher rates of death, MI, or the need for repeat revascularization, 20% versus 17%; death or MI, 9.3% versus 7.6%; and death, 7.4% versus 5.8%. The authors conclude that endoscopic vein harvesting is associated with vein graft failure and adverse clinical outcomes. This study demonstrates some of the potential downsides of endoscopic vein harvesting and must alert surgeons to the possibility of diminished outcomes compared with standard open saphenous vein harvesting. However, this study was not randomized, which is a major shortcoming. It is possible that because of selection bias, those patients at higher risk were assigned to open harvesting. This could have lead to the observed results. However, before surgeons abandon endoscopic vein harvesting, other trials, hopefully randomized and controlled, should be performed.

Patients undergoing peripheral vascular surgery often suffer cardiovascular complications. In the next study [3], Schouten et al. examined 500 patients who had not previously been treated with a statin to receive, in addition to a β-blocker, either 80 mg of extended-release fluvastatin or placebo once daily before undergoing vascular surgery. Postoperative myocardial ischemia occurred in 11% of patients within 30 days in the fluvastatin group and 19% of patients in the placebo group. Death from cardiovascular causes or MI occurred in 5% in the fluvastatin group versus 10% in the placebo group. The authors conclude that in patients undergoing vascular surgery, perioperative fluvastatin was associated with a significant improvement in postoperative cardiac outcome. The study underscores the importance of treatment with statins and optimization of care in patients undergoing cardiovascular procedures. Statin therapy has a major role in the treatment of patients with atherosclerotic cardiovascular disease because their use is associated with a reduction in the incidence of cardiovascular events. Previous studies examining the effects of statins around the time of cardiovascular surgery have largely been equivocal. The benefit of statins is probably more related to anti-inflammatory effects than its effect on cholesterol lowering. This study underscores the benefit of optimization of medical care with statin therapy and β-blockade in the setting of vascular surgery.

Cardiovascular procedures are tending to become less invasive. In the next study, McGinn and colleagues [4] examined the feasibility and safety of minimally invasive surgical coronary bypass grafting (MICS CABG) using port access and a small incision approach. This is a novel approach to the surgical treatment of patients with coronary disease and may be performed with or without the use of cardiopulmonary bypass. During the operation, an apical positioner and epicardial stabilizer are introduced into the chest through the subxiphoid and left seventh intercostal spaces, respectively. The left internal thoracic artery is used to graft the left anterior descending artery, and radial artery or saphenous vein segments were used to graft the lateral and inferior myocardial regions. The mean number of grafts performed was 2.1 + 0.7 with complete revascularization performed in 95% of patients. There was a 7.6% utilization of cardiopulmonary bypass, a 3.8% conversion to sternotomy, and a 2.2% return to the operating room for bleeding. Perioperative mortality occurred in 1.3% of patients. The study demonstrated that MICS CABG is feasible and that the short-term outcomes are excellent. However, there are several limitations of the study. The study was performed in two centers by two operators with excellent technical abilities, but there was no comparison with other techniques. It is questionable how universally this procedure can be applied. The low number of bypasses performed (just over two per patient) suggests that this is not an average or typical group of CABG patients, and that the patients were "cherry picked." The authors admit there is an extensive learning curve. Although the cosmetic result is obviously better compared with a standard sternotomy incision, this study does not demonstrate improved short- or long-term outcomes or provide better graft patency or survival, which would suggest an improvement over current techniques. However, this is a major change in the way coronary bypass surgery could be performed. MICS CABG may potentially make multivessel minimally invasive surgery more effective and more widely available. However, careful surveillance of the results and a comparison with other techniques of on- and off-pump surgical revascularization will need to be performed. Even a slight reduction in the quality of the operations may make this procedure ill advised.

The next study [5] compared percutaneous coronary intervention (PCI) and CABG for the treatment of persons with previously untreated three-vessel or left main coronary artery disease. For the 1,800 patients randomized, the local cardiac surgeon and interventional cardiologist determined that the equivalent anatomic revascularization could be achieved with either treatment. The primary end point was the incidence of a major adverse cardiac or cerebrovascular event (death from any cause, stroke, MI, or repeat revascularization) during the 12-month period after randomization. Rates of major adverse cardiac or cerebrovascular events at 12 months were significantly higher in the PCI group (18% vs. 12% for CABG), in large part because of an increased rate of repeat revascularization (14% vs. 6%). At 12 months, the rates of death and MI were similar between the two groups. The authors concluded that CABG remains the standard of care for patients with three-vessel or left main coronary artery disease. Coronary bypass, as compared with PCI, resulted in lower rates of the combined end point of major adverse cardiac or cerebrovascular events at 1 year.

Patients with refractory heart failure have a poor prognosis. Transplantation remains the best treatment option for these patients with end-stage heart failure. Unfortunately, only about 2,000 transplants are performed yearly in the United States. In addition, the cost is prohibitive under current economic conditions. The next paper by Jones et al. [6] dealt with surgical ventricular reconstruction (SVR), a procedure which reduces left ventricular volume in patients with heart failure caused by coronary artery disease. This paper summarized the results of the Surgical Treatment for Ischemic Heart Failure (STICH) trial. In this trial, SVR with CABG was compared with CABG alone with regard to a reduction in rate of death and hospitalization for cardiac causes. One thousand patients with an ejection fraction of 35% or less having coronary artery disease that was amenable to CABG and left ventricular dysfunction that was amenable to SVR were randomized. The primary outcome was a composite of death from any cause and hospitalization for cardiac causes with a median follow-up of 48 months. SVR reduced the end-systolic volume index by 19% as compared with a reduction of 6% with CABG alone. However, cardiac symptoms and exercise tolerance improved from baseline to a similar degree in both study groups. No difference was observed in the primary outcome that occurred in 59% patients in the CABG group compared with 58% who were assigned to undergo CABG with SVR. The authors conclude that adding SVR to CABG reduced left ventricle volume as compared with CABG alone, but this anatomic change was not associated with a greater improvement in symptoms or exercise tolerance or with a reduction in the rate of death or hospitalization for cardiac causes. Nontransplant options to treat patients with heart failure due to coronary disease have been advocated for many years. Indeed, the best method of SVR to treat these patients has been hotly debated. This study suggests that the optimal method of SVR is no better than CABG alone.

Patients with advanced heart failure purportedly have improved survival rates and quality of life when treated with implanted left ventricular assist devices as compared with medical therapy. Compared with the conventional pulsatile devices, new continuous-flow devices are smaller and may be more durable than the older devices. In this trial [7], the HeartMate II destination-therapy trial randomized 200 transplant-ineligible patients in a 2:1 ratio to either HeartMate II or the first-generation HeartMate XVE pulsatile pump. The patients had New York Heart Association class 3B or 4 heart-failure symptoms with a mean left ventricular ejection fraction of 17%, and 80% were on intravenous inotropes. The primary composite end point was, at 2 years, survival free from disabling stroke and reoperation to repair or replace the device. The primary composite end point was achieved in more patients with continuous-flow devices than with pulsatile-flow devices (46% vs. 11%), and patients with continuous-flow devices had superior actuarial survival rates at 2 years (58% vs. 24%). The rates of disabling stroke were the same in both groups, 11% for the HeartMate II versus 12% for the XVE. The difference in stroke- or surgery-free survival, the primary end point of the study, was driven mainly by a difference in the need to reoperate to repair or replace HeartMate XVEs, with 10% of HeartMate II devices requiring repair or replacement versus 36% of the HeartMate XVE left ventricular assist devices. The quality of life and functional capacity improved significantly in both groups. In summary, the HeartMate II was associated with significant reduction in adverse events, including hospitalizations, sepsis, nondevice- and device-related infection, right heart failure, and arrhythmias versus the XVE. This trial demonstrates the improved efficacy of newer generation ventricular assist devices in patients not eligible for transplantation. Although the results are improving, they need to be much better and less expensive before these devices will play a significant role in the treatment of patients with heart failure. Improvements in technology may offer mechanical assistance as a reasonable option for these patients, but currently available devices will not fit the need.

These studies demonstrate the ongoing efforts at improving the results of cardiovascular surgical interventions. Minimally invasive revascularization techniques are being developed, as are pharmacologically induced improvements, and methods to improve outcomes in patients with heart failure. Although the outcomes are generally excellent with the currently available techniques, more clinical research will be required, but these efforts are likely to lead to improved optimization of care.

References

  1. Shroyer AL, Grover FL, Hattler B, et al. On-pump versus off-pump, coronary-artery bypass surgery. N Engl J Med 2009;361(19):1827-1837.
  2. Lopes RD, Hafley GE, Allen KB, et al. Endoscopic versus open vein graft harvesting in coronary artery bypass surgery. N Engl J Med 2009;361(3):235-244.
  3. Schouten O, Boersma E, Hoeks SE, et al. Fluvastatin and perioperative events in patients undergoing vascular surgery. N Engl J Med 2009;361(10):980-989.
  4. McGinn JT Jr, Usman S, Lapierre H, et al. Minimally invasive coronary artery bypass grafting: dual-center experience in 450 consecutive patients. Circulation 2009;120(11Suppl):S78-S84.
  5. Serruys PW, Morice MC, Kappetein AP, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med 2009;360(10):961-972.
  6. Jones RH, Velazquez EJ, Michler RE, et al. Coronary bypass surgery with or without surgical ventricular reconstruction. N Engl J Med 2009;360(17):1705-1717.
  7. Slaughter MS, Rogers JG, Milano CA, et al. Advanced heart failure treated with continuous-flow left ventricular assist device. N Engl J Med 2009;361:2241-2251.

-- The opinions expressed in this commentary are not necessarily those of the editors or of the American Heart Association --
 

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