The Doctor's Channel - Medical Students

Cardiac catheterization has low diagnostic yield

2010-03-11T22:49:39+00:00

NEW YORK (Reuters Health) – Just 38% of patients with suspected cardiac disease are found to have obstructive coronary disease on elective cardiac catheterization, new research shows. This low diagnostic yield suggests that clinical assessments and noninvasive tests are not doing their job in selecting patients for cardiac catheterization.

“Guidelines recommend continued observation in the case of patients who are at very low risk, noninvasive stress testing to determine the need for cardiac catheterization in the case of patients at intermediate risk, and direct referral for catheterization in the case of patients at high risk,” lead author Dr. Manesh R. Patel and colleagues note.

But whether these recommendations help limit the number of patients without coronary disease who undergo cardiac catheterization was unclear, according to the report in The New England Journal of Medicine for March 11.

To investigate, Dr. Patel, from Duke University Medical Center, Durham, North Carolina, and colleagues analyzed national registry data on nearly 400,000 patients without known coronary disease who had elective cardiac catheterization at 663 hospitals in the U.S.

Obstructive coronary disease was defined as stenosis of at least 50% of the diameter of the left main coronary artery or stenosis of at least 70% of the diameter of a major epicardial vessel.

The median patient age was 61 years and 52.7% of patients were male. Twenty-six percent of subjects had diabetes and 69.6% had hypertension. Roughly 84% had noninvasive tests before cardiac catheterization.

Only 37.6% of patients had obstructive coronary disease at catheterization, the report indicates. Moreover, 39.2% of patients had no coronary disease (stenosis <20% in all vessels).

A positive noninvasive test result slightly increased the likelihood of finding obstructive disease: 41.0% vs. 35.0% (adjusted odds ratio, 1.28, p < 0.001).

In an editorial, Dr. David J. Brenner from Columbia University Medical Center in New York agrees with the authors that a better “gatekeeper” test is needed to select the best candidate for cardiac catheterization. “Ironically,” he notes, “there is evidence that, in many situations, a better gatekeeper test may be yet another radiographic imaging technique—namely, multidetector-row computed-tomographic angiography.”

Reference:
N Engl J Med 2010;362:886-895,943-945.

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Endoscopic resection for Barrett's esophagus usually avoids surgery

2010-03-11T22:47:25+00:00

NEW YORK (Reuters Health) - In patients with Barrett's high-grade dysplasia or early esophageal adenocarcinoma, endoscopic resection improves staging and "dramatically" reduces esophagectomy rates, Australian physicians report.

Esophagectomy, the standard of care, produces high morbidity, and mortality from the procedure ranges from 4% to 20%, according to the researchers. Moreover, the surgery is often done on the basis of biopsy results alone, but biopsy staging is not very accurate.

For these reasons, endoscopic resection is becoming more popular for staging and management, Dr. Michael J. Bourke, from Westmead Hospital in Sydney, and his colleagues say in their article, published online on February 23rd by the American Journal of Gastroenterology.

The researchers studied 75 consecutive patients (ages 45 to 87) who underwent endoscopic resection for biopsy-proven Barrett's high-grade dysplasia or esophageal adenocarcinoma. The mean follow-up was 31 months.

Barrett's mucosa ranged in length from 1 to 16 cm, with a mean of 3.6 cm. In 35 otherwise healthy patients younger than 75, with Barrett's segments no longer than 3 cm, the authors attempted complete excision by 2- to 3-stage radical mucosectomy - which was successful in 33 cases (94%). One patient required esophagectomy; in another, comorbidities interfered.

Among the remaining 40 patients, 8 developed metachronous lesions. Another 5 had esophagectomy because resection revealed submucosal invasion, but there was no recurrence at endoscopic resection sites. Four patients (ages 81 to 92 years) died, but none of the deaths was due to adenocarcinoma.

The authors staged the resections over at least two sessions six weeks apart to minimize the risk of strictures. The number of sessions ranged from one to five per patient, with a median of two resections at the index procedure.

Overall, histologic findings led to changes in grade or stage in nearly half of patients, with lesions downgraded/staged in 21 patients and upgraded/staged in 15. Diagnoses "included the full spectrum of pathology," the authors report, ranging from no dysplasia to submucosal invasive adenocarcinoma. Seventeen patients had only low-grade dysplasia or none at all.

"Nearly one in four patients would have undergone unnecessary esophagectomy if surgery based on biopsy alone was the first-line therapy" in their series, the authors point out.

Unlike biopsy, endoscopic resection also adds data on breadth, depth, and areas of more advanced pathology. Furthermore, because mucosal lesions have a very low rate of nodal involvement, endoscopic resection is likely to be curative, the investigators note.

The absence of serious procedure-related complications in this series "further enhances" the potential utility of endoscopic resection "as a low-risk definitive dysplasia grading and local T-staging tool," Dr. Bourke and associates write.

In conclusion, they say, "We believe it is no longer acceptable to refer patients with early disease for esophagectomy without including endoscopic resection in the preoperative staging strategy."

Reference:
Am J Gastroenterol 2010.

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Women benefit as much as men from statins for primary prevention of CVD

2010-03-11T22:44:28+00:00

NEW YORK (Reuters Health) - Statin use by women cuts their risk of primary cardiovascular disease (CVD) events by roughly a third, which is similar to the risk reduction seen in men, research shows.

"Statin therapy in women without CVD is controversial, given the insufficient evidence of benefit," Dr. Samia Mora, from Brigham and Women's Hospital, Boston, and colleagues note in the March 9th issue of Circulation.

Dr. Mora and colleagues analyzed gender-specific outcomes from the randomized JUPITER trial and performed a meta-analysis of statin trials that focused on women.

JUPITER included 6801 women at least 60 years of age, and 11,001 men at least 50 years of age. All had high C-reactive protein levels (at least 2 mg/L) and normal to low levels of low density lipoprotein cholesterol (no higher than 130 mg/dL). Participants took either rosuvastatin or placebo daily.

The meta-analysis included 7 primary prevention trials, with 13,154 women who had 240 CVD events and 216 deaths.

Compared to the men in the JUPITER trial, the women had lower absolute CVD rates per 100 person-years (0.57 vs. 0.88 for rosuvastatin groups and 1.04 vs. 1.54 for placebo groups) - but both genders had relative risk reductions of roughly 44%.

Further analysis showed that statin therapy significantly reduced revascularization and unstable angina in women, but did not affect other CVD events.

In the meta-analysis, statin use by women cut primary CVD events by 37% (p < 0.001), but did not significantly affect total mortality.

When the results of JUPITER and the meta-analysis are taken together, the researchers conclude, "statin therapy resulted in about a one-third relative reduction in primary CVD in women, a benefit similar to that seen in previous meta-analyses of men."

Reference:
Circulation 2010;121:1069-1077.

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Longer follow-up confirms advantage of sirolimus-eluting vs bare metal stents

2010-03-10T16:43:41+00:00

NEW YORK (Reuters Health) – Three years after ST-segment elevation myocardial infarction (STEMI), sirolimus-eluting stents still provide better protection against major adverse cardiovascular events compared to bare metal stents, new research shows.

The findings are based on 3 years of data from the randomized SESAMI trial. The 1-year results from SESAMI indicated superior outcomes with sirolimus-eluting stents.

Until now, however, long-term safety and efficacy data for sirolimus-eluting stents in STEMI patients came only from registries, according to author Dr. Carmine Musto, from San Camillo Hospital, Rome, and colleagues.

As reported in the February 23rd Journal of the American College of Cardiology, SESAMI included 320 patients, with long-term data available for more than 97% in each group.

The primary outcome – the incidence of major adverse cardiovascular events at 3 years – was 12.7% with sirolimus-eluting stents vs 21% with bare metal stents (p = 0.034). The endpoint was a composite of cardiac and noncardiac death, Q-wave and non-Q-wave infarction, coronary artery bypass graft surgery, or target lesion revascularization.

Patients with sirolimus-eluting stents also had significantly lower rates of target lesion revascularization (7% vs. 13.5%, p = 0.048), target vessel revascularization (8% vs. 16%, p = 0.027), and target vessel failure (11.5% vs. 20.5%, p = 0.028) compared to patients with bare metal stents.

In addition, significantly more sirolimus-treated patients were alive and free from these adverse outcomes (87% to 93%, depending on the event) compared to patients with bare metal stents (79% to 86.5%; p < 0.05). Prevention of target lesion revascularization drove the benefit of the drug-eluting stents, and this was first apparent in the first year of follow-up.

After clopidogrel was discontinued, the two groups had similar cumulative rates of death and recurrent myocardial infarction, the report indicates.

The study had two principal limitations, the authors note. First, it examined only clinical endpoints. Second, it was not powered to detect differences in cardiac event rates between 12 and 36 months.

Reference:
J Am Coll Cardiol 2010;55:810-814.

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Continuous intraperitoneal insulin linked with better quality of life

2010-03-10T16:36:00+00:00

NEW YORK (Reuters Health) - Patients report higher quality of life with continuous intraperitoneal versus subcutaneous insulin, Dutch investigators have found.

The researchers had previously reported that continuous intraperitoneal insulin allows better glycemic control compared to intensified subcutaneous insulin therapy (see Reuters Health story, August 11, 2009).

Their new paper reports on health-related quality of life outcomes and treatment satisfaction in 23 adults with type 1 diabetes who enrolled in a randomized cross-over trial of the two approaches. Patients had 6 months of intensive subcutaneous insulin followed by 6 months of peritoneal infusion, or vice versa. The subcutaneous insulin was given either continuously or via injection - whatever the patient was doing before enrollment.

In their article, published online February 25th in Diabetes Care, lead author Dr. Susan J. Logtenberg, from Isala Clinics, Zwolle, and colleagues write that scores on six subscales of the 36-item Short-Form Health Survey were significantly higher with peritoneal infusion. The only exceptions were in the social functioning and bodily pain domains.

On the World Health Organization-Five Well-Being Index, significantly fewer patients had a score below 50 -- an indication of poor emotional well-being - after peritoneal treatment (6 vs 13, p = 0.02).

Moreover, patients perceived significantly fewer hypoglycemic and hyperglycemic events during their peritoneal infusion phase, leading to greater treatment satisfaction.

As the authors point out, patients preferred the peritoneal approach despite the fact that it requires hospital admission and surgery to insert the pump. It also costs more than twice as much as continuous subcutaneous insulin infusion.

"Continuous intraperitoneal insulin infusion should be (re)considered as a treatment option, at least when satisfactory results of treatment are not reached with subcutaneous intensive insulin treatment regimens," Dr. Logtenberg's team concludes.

Medtronic Europe, which sells insulin pumps, provided an unrestricted grant to the authors.

Reference:
Diabetes Care 2010.

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Melamine-related kidney stones can be managed conservatively

2010-03-10T16:32:38+00:00

NEW YORK (Reuters Health) - Kidney stones linked to melamine-tainted infant milk formula can usually be managed conservatively, Chinese authors report. For infants with renal failure, hemodialysis without surgery was usually adequate.

In August 2008, Chinese officials reported that melamine had been illegally added to some milk-based formulas to increase the protein content. Since then, several young children who drank the tainted milk have died and thousands have developed kidney stones. (See Reuters Health reports September 12 and December 2, 2008.)

In a paper scheduled for publication in the April Journal of Urology, Dr. Jian Guo Wen and colleagues at the First Affiliated Hospital of Zhengzhou University report that in their region, more than 3,000 children came for free medical evaluations after ingesting melamine-tainted formula. In 165, the researchers diagnosed melamine related urinary stones. Fifty children (mean age 23.4 months) had bilateral stones.

The children in this subgroup drank the formula for an average of roughly one year, the authors said. Thirty-one had symptoms, including altered frequency of urination, crying at urination or unexplained crying, and oliguria or anuria. Twenty-eight had mildly acidic urine (pH 6 or less), and 11 had renal failure.

Thirty-three patients had stones ranging from 4-10 mm in diameter (based on ultrasound findings); the other youngsters had smaller calculi. The stones - mainly uric acid and melamine -- were radiolucent on plain x-ray but clearly visible on CT.

Management consisted of hydration, IV sodium bicarbonate 5% to raise urine pH, and an antispasmodic drug (anisodamine 0.1-0.3 mg/kg or atropine 0.1-0.2 mg/kg) to help the stones pass.

Eight of the 11 children with renal failure received up to four sessions of hemodialysis. One patient required ureteral catheterization for a week to drain the renal pelvis.

Children remained in the hospital for an average of 8 days; by discharge, all clinical symptoms resolved. No patient died. Within a month, 33 children passed their stones; in the other 17 youngsters, the stones became smaller.

Despite the good outcomes, the authors advise that "these children need to be monitored for long-term effects of melamine-tainted mild formula consumption."

In a short editorial comment, Dr. John C. Pop at Vanderbilt Children's Hospital, Nashville, Tennessee, disagrees with using hemodialysis to treat renal failure in these children. Instead, he advocates "stenting to relieve the obstruction, followed by conservative treatment" until the stones resolve. He would reserve hemodialysis for patients whose renal insufficiency persists.

Dr. Wen's team defends its management decisions, noting that not all the hemodialysis patients had significant ureteral obstruction. "Hemodialysis was performed according to the regimen issued by the Ministry of Health," and parents of the patients opted for this treatment instead of stenting.

Reference:
J Urol 2010;183:1533-1538.

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Fertility-conserving surgery safe for early cervical cancer

2010-03-09T16:57:54+00:00

NEW YORK (Reuters Health) – In young women with stage IA1 cervical cancer, a fertility-preserving conization does not reduce survival compared to hysterectomy, researchers report in the March Obstetrics and Gynecology.

With either procedure, 5-year survival is excellent, approaching 100%, the findings indicate.

Small series and case control studies have suggested that conization is safe, but large studies comparing conization and hysterectomy for stage IA1 cervical cancer have been lacking until now, according to lead author Dr. Jason D. Wright, from Columbia University College of Physician and Surgeons, New York, and colleagues.

For the current analysis, the researchers used data from the Surveillance, Epidemiology, and End Results database from 1988 to 2005. They identified 1409 women, age 40 or younger, with stage IA1 cervical cancer; 841 had hysterectomy and 568 underwent conization.

On logistic regression analysis, predictors of conization included Asian ethnicity, single status, diagnosis later in the study period, and residence in the eastern United States. In addition, women younger than 30 had a 78% higher likelihood of conization compared to women above 35.

At 5 years, 98% of those treated with conization and 99% treated with hysterectomy were alive.

“Our study suggests that fertility-conserving surgery is safe for young women with stage IA1 squamous cell carcinoma of the cervix,” the authors conclude. “Young women with microinvasive cervical tumors should weigh the risks and benefits of conization in the context of individual preferences and tumor characteristics.”

Reference:
Obstet Gynecol 2010;115:585-590.

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Tenofovir-related renal dysfunction can't always be reversed

2010-03-09T16:55:19+00:00

NEW YORK (Reuters Health) - Tenofovir nephrotoxicity can't always be fully reversed in HIV-infected men, according to a new study.

Up to 2% of patients have adverse renal effects from the nucleotide reverse transcriptase inhibitor, and reportedly, kidney function rapidly normalizes when tenofovir is stopped. But "because of the few cases, limited follow-up and the insensitive measure used" (serum creatinine) in the previous reports, it's not known how reversible the nephrotoxicity really is, note senior author Dr. Andrew Carr, from St. Vincent's Hospital, Sydney, Australia, and colleagues.

In a paper published online February 19th in the Journal of Acquired Immune Deficiency Syndromes, Dr. Carr and his associates describe 24 men who discontinued tenofovir because their estimated glomerular filtration rate (eGFR) was less than 60 ml/minute/1.73 m2.

During a median of 30 months between start of tenofovir and drug cessation, median eGFR fell from 74 to 51 ml/min/1.73 m2 - a reduction about 10 times greater than expected with normal aging.

During the median period of 13 months after tenofovir discontinuation, eGFR rose by a median of 19 ml/min/1.73 m2. Most improvement occurred in the first month.

In only 10 (42%) patients did eGFR return to pre-tenofovir levels, and only two exceeded 90 ml/min/1.73 m2.

Twelve patients had eGFR increases above the median; this group had a more rapid monthly decline while on tenofovir compared to those with less improvement (1.9 vs 0.7 ml/min/1.73 m2, p = 0.009) and a shorter duration of tenofovir therapy (21 vs 51 months, p = 0.08), suggesting that "more acute renal damage is less likely to be permanent."

These patients were also more likely to have received protease inhibitors (100% vs 54%, p = 0.02). The authors explain that protease inhibitors can increase tenofovir levels in plasma and renal tubular epithelium. Therefore, the greater improvement was likely due to cessation of higher tenofovir exposure.

The single-center study was retrospective, relatively small and had a variable duration of follow-up, and so prospective validation in a larger, more heterogeneous population is needed, the researchers say.

Nevertheless, they conclude, earlier discontinuation of tenofovir might have led to greater improvements in renal function, "which underlines the importance of regular assessment and perhaps of earlier intervention."

Specifically, they advise, even gradual deterioration in eGFR to levels above 60 ml/min/1.73 m2 might be cause enough to discontinue tenofovir.

Reference:
J Acquir Immune Defic Syndr 2010.

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Emboli filters during PCI lead to higher risk of stent thrombosis

2010-03-09T16:49:30+00:00

NEW YORK (Reuters Health) - Using a distal filter to protect against emboli during coronary stent implantation increases long-term rates of stent thrombosis and target vessel revascularization, investigators in Denmark report.

Randomized trials have shown no benefit of distal protection in the short or intermediate term after percutaneous coronary intervention (PCI), Dr. Anne Kaltoft from Aarhus University Hospital, Skejby, and her associates note. Their article in the Journal of the American College of Cardiology for March 2 reports their 15-month follow-up of patients treated for ST-elevation myocardial infarction in the DEDICATION trial.

Patients received aspirin, clopidogrel, and unfractionated heparin in advance of the procedure. If a cardiologist believed that a wire filter could be advanced (based on pre-dilation and initial visualization of the peripheral vascular bed), the researchers then randomized the patient either to distal protection (n = 312) or conventional treatment (n = 314).

In the distal protection group, filter placement was attempted in 304 patients (97%) and was successful in 254 patients (81%).

But filter protection afforded no benefit at either 30 days, 6 months, or 15 months later, the researchers said.

Nine cases of definite stent thrombosis occurred in the protection group and one in the control group (2.9% vs 0.3%, p = 0.01).

The rate of target lesion revascularization was also significantly increased in the distal protection group (12.5% vs 7%, p = 0.05), as was the rate of target vessel revascularization (15.4% vs 8.3%, p < 0.01).

The two groups had similar rates of myocardial infarction and mortality.

Dr. Kaltoft's team suggests that vessel spasm in response to filter placement could lead "to an underestimation of the vessel diameter and to undersizing of the implanted stent, a known predictor of early stent thrombosis." Other possibilities include damage to the vessel wall at the site of filter deployment or stent apposition during filter retrieval.

Similarly, damage to the vessel wall from pre-dilation or during placement of the filter could increase restenosis rates and the need for repeat revascularization.

Whatever the cause, the authors conclude, "Routine use of a filter wire in its present form cannot be advocated and probably should be avoided with primary PCI for ST-elevation myocardial infarction."

Reference:
J Am Coll Cardiol 2010;55:867-871.

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African American kids with diabetes have higher HbA1c levels

2010-03-08T19:20:13+00:00

NEW YORK (Reuters Health) - As in adult diabetics, hemoglobin (Hb) A1c levels are higher in black children with type 1 disease than in white children, independent of mean blood glucose, according to a February 25th online report in Diabetes Care.

The authors of the report have long been interested in between-individual differences in HbA1c levels. Spurred by reports indicating a role for race and ethnicity in adult diabetic variables, lead author Dr. Jodi L. Kamps and colleagues at Louisiana State University Health Sciences Center in New Orleans looked for a similar pattern in their pediatric patients.

Their study included 276 children (72% Caucasian, 28% African-American) with an average age of 12.5 years and an average disease duration of 4.9 years. Slightly more than half were girls.

Mean blood glucose was determined by averaging data downloaded from patient glucose meters for periods of 30 days or more. Predicted HbA1c was calculated with the following equation:

HbA1c % = (mean blood glucose x 0.021) + 4.3

Hemoglobin glycation index was then calculated by subtracting the predicted HbA1c from the observed HbA1c.

The hemoglobin glycation index was significantly higher in the African-American children (p < 0.001), the authors report. They note that the highest tertile (index > 0.26) contained 57.5% of the African American children but only 24.2% of the Caucasian children. The adjusted mean hemoglobin glycation index values were 0.64 in black children and -0.15 in whites (p < 0.001).

Furthermore, average HbA1c was significantly higher among African Americans than Caucasians after controlling for mean blood glucose, age, and diabetes duration: 9.1% vs 8.3%, respectively (p < 0.001).

These findings may help explain why African Americans are at increased risk of diabetes complications, the authors suggest.

Also, they caution, "Given that mean blood glucose-independent disparity in HbA1c is unlikely to be modifiable by glucose lowering agents, simply increasing insulin doses in order to achieve a lowered target HbA1c could lead to greater risk of hypoglycemia in African American patients."

Dr. Kamps and her associates advise that both HbA1c and mean blood glucose be taken into account when making therapeutic decisions for diabetics, especially for African Americans.

Reference:
Diabetes Care 2010.

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