Research from Renal Week, San Diego, California, November 14-19, 2006 and other cardiac news

Cardiology Review® Online, January 2007, Volume 24, Issue 1

Following recent reports of late in-stent rethrombosis in drug-eluting stents, the American Heart Association (AHA) released a position statement emphasizing the use of antiplatelet therapy following stent placement.

The American Heart Association weighs in on drug-eluting stents and rethrombosis

The December 5, 2006 statement pointed out that existing clinical guidelines from the AHA, the American College of Cardiology, and the Society for Coronary Angiography Intervention recommend antiplatelet therapy for 1 to 12 months after a stent procedure, but that many patients do not adhere to this postoperative therapy.

Raymond J. Gibbons, MD, the president of the AHA and professor of medicine at the Mayo Clinic College of Medicine, experienced this nonadherence firsthand just as the statement was released. When counseling a patient who had a drug-eluting stent implanted on the necessity of aspirin use, the patient remarked that “no one had told him” about the importance of clopidogrel and aspirin.

We “need to focus attention on this issue,” said Dr Gibbons. “Everyone should be on aspirin. In a recent study, 25% of patients were not taking aspirin, and many current studies do not even report aspirin usage.”

The statement also cautioned that data on late in-stent rethrombosis is conflicting and that further research in this area is necessary. Until that research is complete, Gibbons urged physicians to adhere to practice guidelines when treating patients. Aspirin treatment will likely have to be continued indefinitely, said Dr Gibbons, and patients should not modify treatment without consulting their cardiologist.

A statement offering additional guidance on this issue is being drafted by the AHA in collaboration with 5 other major medical organizations, and should be available before the start of 2007, said Dr Gibbons.

Two studies presented at The American Society of Nephrology’s 39th Annual Meeting and Scientific Exposition (or Renal Week) highlighted the connections between cardiovascular conditions and later development of kidney disease.

Research at Renal Week 2006 examines links between the kidney and cardiovascular disease

In the first study, researchers analyzed data on 4782 women with a high family risk of hypertension and identified 643 with high blood pressure during pregnancy. These individuals were compared with women who had pregnancies without hypertension or who never had a pregnancy lasting longer than 6 months. Rates of cardiovascular disease (CVD), including heart attack and stroke, were the outcomes studied.

Women having hypertension during pregnancy had significantly higher rates of CVD events after age 40. Compared with normotensive women, these women had a doubled risk of stroke, a 1.5 times higher risk of a coronary heart disease event, and a 1.5 times greater likelihood of developing high blood pressure. Hypertension during pregnancy was also associated with increased risk of microalbuminuria, an early sign of kidney disease.

Although hypertension affects 10% of pregnancies in the United States and is a leading cause of health problems and death for both mothers and babies, long-term consequences have been underappreciated.

“Traditionally, these hypertensive pregnancy disorders—including a potentially serious complication called pre-eclampsia—have not been considered to have any long-term impact on the mother’s health,” said lead investigator Vesna D. Garovic, MD, assistant professor of medicine at the Mayo Clinic College of Medicine. “However, our results support the role of hypertension during pregnancy as a risk factor for CVD later in life.”

Just how the 2 are connected is unclear. “It may be that hypertension in pregnancy induces long-term metabolic and vascular abnormalities, which may lead to an increase in overall CVD risk” later on, Dr Garovic speculated. In terms of patient care, “doctors should screen for hypertensive disorders of pregnancy” when assessing a woman’s overall risk profile for CVD, Dr Garovic urged. “We suggest that women with hypertensive pregnancies be monitored closely for asymptomatic cardiovascular events and treated aggressively for modifiable risk factors.”

A second study presented at Renal Week 2006 explored the connections between the constellation of symptoms known as the metabolic syndrome and the increased risk of worsening kidney disease among an African-American cohort. This study found that for hypertensive African Americans classified as having the metabolic syndrome, these individuals faced a 38% increased risk of progressive chronic kidney disease (CKD).

Janice P. Lea, MD, of Emory University and colleagues drew on data from a large study of treatment for hypertension in African Americans. Metabolic syndrome was defined as having 3 of 5 of the following conditions: high blood glucose, low high-density lipoprotein (“good”) cholesterol, high triglycerides, obesity, and high blood pressure. Based on this criteria, 25% of the study group had metabolic syndrome.

Four-year follow-up revealed that patients with metabolic syndrome had significantly higher rates (38%) of progressive CKD, which was defined as continued decline in kidney function, end stage renal disease (ESRD), or death. The increased risk of progressive CKD held even after risk adjustment for other factors known to affect kidney disease outcomes, including age, sex, obesity, and initial kidney function level.

On their own, none of the individual metabolic syndrome risk factors was related to progressive CKD; in addition, the increased risk associated with metabolic syndrome was unaffected by which blood pressure treatment the patients received.

“Metabolic syndrome can contribute to worsening kidney disease,” said Dr Lea, and “that’s important, because if we can reduce the severity of metabolic syndrome through diet and medication, it may help to reduce the rate of progressive kidney disease—and thus delay ESRD and the need for dialysis therapy, which is very costly and debilitating.”

The Annals of Internal Medicine

When it comes to cardiac care, those in health maintenance organizations (HMO) or with private insurance do better than those in the Medicaid program, finds a new study published in . Medicaid patients were less likely to receive short term medications and to undergo invasive cardiac procedures. They also had higher in-hospital mortality rates and were less likely to receive recommended discharge care. Mortality was also higher among Medicare patients, although not as high as those in the Medicaid program.

The impact of Insurance coverage on care of patients with acute coronary syndromes

The study, by lead author James Calvin MD, director of cardiology at Rush University Medical Center, and colleagues, evaluated data from more than 37,000 patients < 65 years of age and another 59,000 patients ≥ 65 years at 521 hospitals nationwide who had acute coronary syndromes. Researchers measured the use of the recommended treatment guidelines of the American College of Cardiology and American Heart Association, which include guidance on medications within the first 24 hours, medications and dietary advice to control cholesterol levels, counseling to stop smoking, and cardiac rehabilitation programs.

When compared to patients with HMO or private insurance, Medicaid patients were less likely to receive aspirin, beta blockers, clopidogrel, and lipid-lowering agents. Medicaid patients were also less likely to receive dietary counseling, smoking cessation counseling, and referral for cardiac rehabilitation. Gaps also existed for acute care. Delays were observed for Medicaid patients in the time to first electrocardiogram and in time to cardiac catheterization and revascularization when these procedures were performed.

Medicaid patients had higher in-hospital mortality rates (2.9% vs 1.2%) and after adjustment, the risk for death was approximately 30% higher in Medicaid patients compared with those in HMOs and private insurance plans. Mortality rates were not significantly different for Medicare patients.

“It is reassuring to find that the Medicare system for our older Americans appears to be working, but disappointing to find insurance status affects quality of care and clinical outcomes for cardiac patients under the age of 65,” said Calvin.

The study urges more investigation to determine the root cause of these disparities and develop novel strategies for narrowing the gaps in quality. According to Calvin, it’s not simply an issue of economic gain.

“On the surface people may conclude that doctors have a bias against poor people. However, it doesn’t cost a thing to tell someone to watch the salt in their diet or to quit smoking, which is really good advice to reduce heart problems,” said Calvin. “We need further study to determine if system problems, such as lack of computerized record keeping or not enough nurses contribute to this disparity. Care by a noncardiologist may also be partly responsible.”

The full study can be found in Ann Intern Med. 2006;145(10):739-748.