Journal watch

Recent studies about acute MI reperfusion times, cardiac resynchronization therapy, and and other topics.


Statewide system improves reperfusion times for acute MI

A statewide system in North Carolina substantially improved coronary reperfusion times for patients with acute ST-segment elevation myocardial infarction (STEMI), a study reported.

The Reperfusion of Acute Myocardial Infarction in North Carolina Emergency Departments (RACE) study set out to determine whether establishing a statewide system for reperfusion would result in more rapid treatment and more appropriate therapy for eligible patients. The study involved 10 hospitals that offered percutaneous coronary intervention (PCI) and 55 hospitals that didn't. Participating PCI hospitals agreed to allow ED physicians or paramedics to activate the catheterization laboratory at any time with one telephone call and accept incoming STEMI patients regardless of bed availability, among other requirements.

Regional coordinators and representatives from the PCI hospitals worked with the non-PCI hospitals to discuss coordination of care. Coronary reperfusion plans were established at all of the participating hospitals, focusing on early diagnosis; appropriate on-site therapy; EMS, ED, and catheterization lab processes; and patient transfer. Researchers collected and analyzed data on reperfusion times and rates three months before and three months after the year-long intervention. The results were published online Nov. 4 by the Journal of the American Medical Association.

Median times to reperfusion improved significantly after the intervention was implemented. Door-to-device times decreased from 85 minutes to 74 minutes for primary procedures performed at PCI hospitals and from 165 minutes to 128 minutes for procedures in patients transferred to PCI hospitals. Door-to-needle times decreased from 35 to 29 minutes at non-PCI hospitals, and “door-in door-out” times for patients transferred from non-PCI to PCI hospitals decreased from 120 minutes to 71 minutes. Clinical outcomes, including death and cardiac arrest, did not change significantly after the intervention in patients who presented to or were transferred to PCI hospitals.

The researchers concluded that this statewide, regionally based intervention substantially improved quality of care in patients with STEMI, attributing its success in part to its involvement of all hospital and EMS systems and use of regional coordinators. However, they wrote, more research is needed to determine whether such programs can reduce STEMI-related morbidity and mortality.

Cardiac resynchronization therapy of little benefit in some heart failure patients, study finds

Patients with moderate to severe heart failure and a narrow QRS interval may not benefit from cardiac resynchronization therapy (CRT), according to a study.

Researchers performed a randomized, double-blind trial to determine whether CRT would benefit patients with narrow QRS syndromes and left ventricular mechanical dyssynchrony. Patients were eligible to participate if they had moderate chronic heart failure due to ischemic or nonischemic cardiomyopathy, an ejection fraction less than 0.35 and a QRS interval less than 130 ms. One hundred seventy-two patients were randomly assigned to receive CRT or no CRT and underwent cardiopulmonary exercise testing at six months. The primary end point was an increase in peak oxygen consumption of 1.0 mL per kg of body weight per minute or greater. The study results were published online Nov. 6 by the New England Journal of Medicine.

At six months, the CRT and control groups did not differ significantly in achievement of the primary end point (46% vs. 41%, respectively). In subgroup analyses, oxygen consumption increased in patients with prolonged QRS intervals who received CRT but did not change in patients with narrow QRS intervals. Although a greater proportion of patients in the control group than in the CRT group had heart failure events that required intravenous therapy (22.3% vs. 16.1%), the difference was not statistically significant.

The authors noted that their method of identifying mechanical dyssynchrony may have affected the study results because it lacked specificity. However, they concluded that CRT is not effective for improving peak oxygen consumption in patients with moderate heart failure, mechanical dyssynchrony and a QRS interval less than 130 ms.

Mental health issues in returning soldiers more common than thought

U.S. veterans are more likely to have mental health problems three to six months after returning from Iraq than when they first come home, a study found.

The longitudinal study assessed 88,235 U.S. soldiers via a self-report questionnaire and two brief interviews with a health provider upon their immediate return from Iraq and an average of six months later. The soldiers' mean age was 30.4 years; 91% were men. They were screened for posttraumatic stress disorder (PTSD), major depression, alcohol misuse or other mental health problems. The study was published in the November 14 Journal of the American Medical Association.

Subjects reported more mental health distress, and were referred for mental health services at higher rates, in the second assessment. Reservist and National Guard units had higher rates than active-duty soldiers, as well. Between the first and second assessment, PTSD reports rose from 11.8% to 16.7% for active soldiers and from 12.7% to 24.5% for reserve soldiers. Also changed were depression (active 4.7% to 10.3%; reserve, 3.8% to 13%), concern about interpersonal conflict (active 3.5% to 14%; reserve 4.2% to 21%), and overall mental health risk (active 17% to 27%; reserve 17.5% to 35.5%).

Reservists may have higher rates of mental health problems at the second assessment than active-duty soldiers, in part because of the stress of transition into civilian employment and the lack of day-to-day support from military peers, the authors said. Combining the first and second assessments revealed that 20.3% of active-duty soldiers and 42.4% of reserve soldiers needed mental health treatment within six months of returning home from Iraq. Clinicians should be aware of the risk and the importance of intervening as early as possible, the authors said.

Overuse of CT scans may be increasing cancer risks

Physicians may be overusing computed tomography (CT) scanning as a diagnostic tool, thus unnecessarily increasing patients' risk of cancer from radiation exposure, a recent study reported.

While CT scanning represents perhaps the single most important advance in diagnostic radiology, researchers said, it also involves much higher doses of radiation than plain-film radiography. Using data on CT scan use combined with individual risk estimates, researchers estimated that 1.5% to 2% of all cancers in the U.S. may be attributable to radiation from CT scans. The review article appeared in the Nov. 29 New England Journal of Medicine.

Follow-up studies of atomic-bomb survivors have provided more than 50 years of data on radiation-related cancer risks among adults and children who were exposed to the same range of organ doses as those delivered during CT studies, the authors said. Even though most diagnostic CT scans have a favorable ratio of benefit to risk, they said, studies have questioned its use in specific situations, such as blunt trauma, seizures, chronic headaches and for diagnosing acute appendicitis in children.

Particularly worrisome, the authors noted, is the use of CT scans as part of defensive medicine or repeated scans due to lack of communication throughout the medical system. Also problematic, they said, is the fact that many physicians underestimate the risks of CT scans compared with other radiologic studies.

The authors recommended three strategies to reduce overall radiation exposure:

  • Reduce the CT-related dose in individual patients by, for example, using the automatic exposure control option in the latest scanners;
  • Replace CT use whenever practical with other options, such as ultrasonography and magnetic resonance imaging; and
  • Decrease the number of CT studies prescribed, considering that an estimated one-third of all CT scans are not justified by medical need, leading to more than 20 million U.S. adults and 1 million children per year being unnecessarily exposed to potentially dangerous levels of radiation.

New measure of hemoglobin predicts mortality in dialysis patients

Variability in hemoglobin levels is a strong predictor of mortality in patients with end-stage renal disease, according to a study of dialysis patients.

In the study of about 35,000 dialysis patients, researchers used a new metric called Hb-Var, which measures variability of hemoglobin levels independent of absolute values and trends over time. The study found that greater hemoglobin variability, as measured by higher Hb-Var scores, predicted mortality in the patients. After adjusting for other factors, they determined that each 1 gram/deciliter increase in Hb-Var resulted in a 33% increased risk of death.

The study found that the relationship between Hb-Var and mortality remained significant after adjustment for absolute hemoglobin levels and trends in hemoglobin levels over time.

They also determined that patient characteristics accounted for very little of the variation in the variability metric, and concluded that greater hemoglobin variability is independently associated with higher mortality. The study appeared in the December issue of the Journal of the American Society of Nephrology.

Based on the study results, Hb-Var may be a valuable measurement of the effects of low hemoglobin in end-stage renal disease, study authors said. The findings could eventually lead to changes in the management of anemia, such as adjustment of the type, dose and timing of treatment with erythropoietin and iron, the authors concluded.

The consistency of results across various modeling strategies, said the authors, supports the theory that Hb-Var represents an important physiologic stress. It was unclear, however, whether the association between Hb-Var and mortality was due to the absence of hemoglobin variability, the absolute hemoglobin level achieved, the absence of temporal hemoglobin trend, or a combination of these factors, said the authors.