(Circulation. 2000;102:e9044.)
© 2000 American Heart Association, Inc.
Cardiovascular News |
Cardiovascular News
Controversy Over Myocardial Revascularization, Either Transmyocardial or Percutaneous, Continues as Experts Spar Over Advantages of Each
In the wake of the controversial results of the Direct Myocardial Revascularization (DMR) In Regeneration of Endomyocardial Channels Trial (DIRECT), proponents of percutaneous myocardial revascularization, transmyocardial revascularization, and permutations of the various techniques sparred over effectiveness and the placebo effect during the Scientific Sessions of the American Heart Association in New Orleans. The proponents of transmyocardial revascularization, led by Kenneth A. Horvath, MD, of Northwestern University Medical School in Chicago, maintained that their procedure differs markedly from the percutaneous method used in the DIRECT trial and should not have been lumped in with the catheter-based techniques.
In transmyocardial revascularization (TMR), the chest is opened and a laser (usually a CO2 laser) is used to open channels through the myocardium. In percutaneous transmyocardial revascularization (PMR), the laser is fed into the heart via the usual catheter route. A cardiologist uses a (usually) less powerful laser to cut small channels into but not through the myocardium.
Dr Horvath reported that 
66% of 78 patients who had
undergone TMR and were then followed for as long as 7 years could be
categorized as having angina classes I or II. Before undergoing the
procedure, the average angina class was 3.7±0.5. Five years after TMR,
the average angina class was 1.6±1
(P=0.0001). Sixty percent of
the patients had a decrease in angina of at least 2
classes.
These results conflict directly with the placebo-controlled DIRECT. The results of DIRECT were first released at the conference "Transcatheter Cardiovascular Therapeutics 2000" in Washington, DC, on October 19, 2000, by Martin Leon, MD, of Lenox Hill Heart and Vascular Institute in New York, NY. Dr Leon reported his study again in New Orleans and stood by his contention that the improvements from such treatments come from an exaggerated placebo effect. In his 14-center study, 298 patients were assigned to low-dose or high-dose laser treatment or to placebo. The laser used was the Biosense DMR system. In the placebo arm, the use of the laser was realistically simulated, and patients did not know what kind of treatment they were getting.
In another study, Gregg Stone, MD, of the Cardiovascular Research Foundation at Lenox Hill Hospital in New York, NY, and colleagues at 17 centers used PMR with an Eclipse holmium-YAG multifiber laser to open a totally occluded artery that could not be opened in another way. Patients received either maximum medical therapy or maximum medical therapy plus PMR.
Dr Stone said his results indicated that the procedure does not seem to reduce angina or increase exercise tolerance markedly at 6 months. However, he noted that "We should wait for the 12-month results" because the laser he used was different from that tested by Dr Leon and, as a result, there might be a difference in the depth of the channels made. According to Dr Stone, "TMR may be totally different. We need triple-blind, placebo-controlled trials with TMR, PMR, and DMR. I also think we need a placebo-controlled trial of TMR."
However, Dr Horvath said he did not think a placebo-controlled trial of TMR alone would be acceptable because the patient’s chest must be opened. Dr Stone countered by noting that many patients have been treated with expensive devices that could have potentially severe complications. He said there would be less harm in subjecting a couple hundred patients to a sham procedure than there would be in treating everyone with devices that are not known to be effective.
Dr Stone is not yet ready to give up on PMR. He said he thinks experts should continue to develop the treatment in an effort to determine if it works and, if so, how.
The major dilemma with all these forms of laser revascularization is that no one knows how they work. At first, surgeons thought they were simply providing a new blood supply to areas of the heart where the arteries were occluded. When it became apparent that the channels were closing up soon after the procedure, they speculated that the procedure could be generating angiogenesis, the growth of collateral circulation, in the ischemic area of the heart.
Another theory was that the laser was somehow killing nerves in the heart, reducing the patient’s ability to sense his or her angina. Dr Horvath said that MRI studies he had done of patients’ hearts indicated that this was not occurring.
Dr Horvath thinks the holmium-YAG lasers used in the percutaneous approach make that procedure less effective. He believes that this laser "has a photoacoustic effect echoing into the tissue. And it takes 15 to 20 pulses to get through the myocardium...I would not use a holmium-YAG laser. It is the worst wavelength of light."
He said the YAG laser treats only the subendocardium. "It is hard to believe you will get as good a response as you get when you treat the whole thickness of myocardium." The CO2 laser used in TMR creates a controlled injury, but it is difficult to determine how much damage the YAG laser creates.
Advocates of Medical Treatment, Surgery, and Percutaneous Coronary Intervention Agree on One Thing
Physicians who use percutaneous transluminal coronary angioplasty (PTCA), coronary bypass graft surgery (CABG), and medical therapy to treat patients with blocked coronary arteries agreed on one thing at a plenary session at the American Heart Association meeting in New Orleans: each of their specialties is getting better. Despite that, representatives from each made strong cases for the validity of their approaches in multivessel disease.
If the use of new techniques in stents and percutaneous interventions (PCIs) proves as beneficial as they promise, then PCI may beat surgery overall in the treatment of multivessel disease, said Richard E. Kuntz, MD, of Brigham and Women’s Medical Center in Boston, Mass. However, as matters now stand, surgery should be considered first for multivessel disease.
Peter Berger, MD, of the Mayo Clinic in Rochester, Minnesota, said there are questions to be considered when a physician must decide between recommending PCI or CABG. However, advances in the designs of guides and stents have made such treatment available to some patients for whom it was impossible in the past. Although stents have reduced the need for revascularization, "it remains true that the need for repeat revascularization is more common after angioplasty than bypass." If a patient wants to undergo only one procedure, then bypass is more appropriate. "Most of the people I treat would rather have two PTCAs than one bypass," he said. Patients prefer that procedure because there is less pain and a shorter recovery time.
Robert Guyton, MD, director of cardiothoracic surgery at Emory University School of Medicine noted that surgeons operate for 2 reasons: "One is to relieve symptoms and the second is prolong life." Patients report sustained improvement in symptoms after CABG at 5 years in a variety of studies. In terms of survival, CABG has been shown to increase life in specific groups of patients, but the increases have been small. "In real world trials, we pick patients for whom the 2 modalities have no difference," he said.
While PTCA was improving, surgery was also getting better. The risk-adjusted mortality from 1988 until 1996 for CABG improved 10% per year during that period. There are indications that mortality could be further reduced by more use of off-pump CABG, he said. The use of spasmolytics and arterial grafts has also improved the surgery. "For the first time, surgery is changing faster than PTCA ... CABG is a very attractive option for patients with multivessel artery disease."
David Waters, MD, of the University of California at San Francisco said one problem with studies comparing maximum medical therapy to CABG and PCI is that none of them use optimal treatment with medication(s). The survival benefit from CABG dissipates after a decade, whereas the benefit from some types of medical therapies increase with time, he said. For example, the studies of lipid-lowering therapies show that the benefits of those drugs persist over time.
One problem is that physicians often know what drugs should be given to patients but they often do not think of those results when they are sitting across from the patient, said Dr Waters. Rather than an incorrect or incomplete diagnosis, physicians are thinking of heart disease in an "inappropriate paradigm," he said. "We think of coronary disease as a pumping and not a metabolic problem. And there is a disbelief in the generalizability of these trials to our patients. Despite the proven benefit of medical therapy, it is greatly underused."
African-Americans Are Less Likely to Receive Life-Saving Care When Faced With Heart Disease
In a series of studies, researchers at the American Heart Association’s Scientific Sessions 2000 again documented the disparity of care received by African-Americans with heart disease. In a study of Medicare records, Judy Battle, MD, an associate professor of medicine at Duke Clinical Research Institute in Durham, NC, and her colleagues discovered 190 000 Medicare patients who would be candidates for an implantable cardioverter defibrillator on the basis of a diagnosis of an abnormal heart rhythm of cardiac arrest. However, they found that white male Medicare patients were twice as likely to receive the implantable device as their African-American female counterparts. Because all the patients were covered by Medicare, the difference was not explained in terms of insurance. This study demonstrates that the disparities in treatment for African-Americans extend to the new technologies such as implantable defibrillators.
A study by David S. Marks, MD, director of the cardiac catheterization laboratory at the Medical College of Wisconsin in Milwaukee, showed that although the 30-day mortality after reperfusion therapy was similar between the races, it changed dramatically at 1 year, with African-Americans being 34% more likely to die. His study included subjects in 3 GUSTO studies. "This is a failure of secondary prevention," he said. Only future study will determine whether that failure is biological or environmental.
African-American patients were likely to delay longer in seeking treatment for symptoms of heart failure than members of other racial and ethnic groups, said Lorraine S. Evangelista, RN, PhD, of the University of California at Los Angeles. Dr Evangelista evaluated the charts of 753 patients admitted with heart failure to a Veterans Affairs Medical Center and found that overall, patients waited 3 days before seeking care for their symptoms. However, African-Americans waited 3.5 days, whereas whites, Asians, and Hispanics waited just under 3 days. African-Americans also had more readmissions to the hospital and more comorbidities. "We feel interventions are needed to address the delay and to help patients recognize the symptoms of heart failure early on," she said.
"Access to care is key," said Dr East. "What we know from prior studies is that when you look at African-Americans patients with ischemic heart diseases, they are less likely to receive therapy. Black patients are younger than their white counterparts. The onset of disease is younger. For some reason, blacks have a disproportionate share of disease and are reaching the hospital at a much earlier age. But for some reason, blacks don’t get into the system and don’t receive the same level of care."
Dr East said that education does not seem to be reaching the African-American community. In part, he said, there may be a problem in patient-physician interaction. "The health beliefs of the patient do matter," he said. There are data on those beliefs; however, "what we don’t have are data on the beliefs of physicians. It is difficult to collect this."
He said that, in the past, many physicians perceived black patients as less compliant with treatment recommendations than patients of other races and ethnic groups. Again, the issue is one of cultural competence. Often, the patient and physician do not understand one another. "Too many blacks are dying of indigestion," he noted.
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