Post-Heart Attack Mortality Rate Has Declined Since 1995

Study also finds decrease in the between-hospital variance for 30-day mortality in patients over 65

20 aug 2009 -- The 30-day mortality rate for older patients released from the hospital after acute myocardial infarction has declined since 1995, according to a study in the Aug. 19 issue of the Journal of the American Medical Association.

Harlan M. Krumholz, M.D., of the Yale University School of Medicine in New Haven, Conn., and colleagues examined data on 2,755,370 patients (ages 65 years and older) and 3,195,672 discharges from nonfederal U.S. acute care hospitals from 1995 to 2006. The data was analyzed to determine hospital-level 30-day risk-standardized mortality rates (RSMRs) for patients discharged with acute myocardial infarction.

The researchers found that the 30-day RSMR decreased from 18.8 percent in 1995 to 15.8 percent in 2006. There were also fewer differences in the rates between hospitals, as the between-hospital variance decreased from 4.4 to 2.9 percent and the interquartile range decreased from 2.8 to 2.1 percent.

"Our study reveals a marked reduction in hospital-level 30-day RSMRs in the United States from 1995 through 2006. In this period, the average hospital-specific 30-day RSMR decreased approximately 3 percent, a nearly one-sixth relative reduction in short-term mortality," the authors conclude.

Several study authors reported contractual relationships with the Colorado Foundation for Medical Care, the American College of Cardiology, and the Oklahoma Foundation for Medical Quality. Two co-authors reported membership on a UnitedHealthcare scientific advisory board.

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MI Seems to Be a Risk Factor for Diabetes

BOSTON, Aug. 24 -- Myocardial infarction more than doubles the risk of new-onset diabetes and leads to a 15-fold increased risk of impaired fasting glucose, according to a study of more than 8,000 MI patients.
During a mean follow-up of 3.2 years post-MI, 3.7% of patients developed diabetes, compared with 0.8% to 1.6% for historical cohort populations with no history of MI, Dariush Mozaffarian, M.D., of Harvard, and colleagues, reported in the Aug. 25 issue of The Lancet.
Additionally, they found, 27.5% of patients developed impaired fasting glucose compared with 1.8% of historical cohorts.
"Our results indicate that myocardial infarction could be a prediabetes risk equivalent," the authors wrote. "Smoking cessation, prevention of weight gain, and consumption of typical Mediterranean foods might lower this risk, which emphasizes the need for guidance on diet and other lifestyle factors for patients who have had a myocardial infarction."
Although diabetes confers a well documented risk of coronary disease and MI, less is known about the impact of MI on subsequent diabetes risk. Dr. Mozaffarian and colleagues retrospectively examined the issue in 8,291 patients who had had an MI within the previous three months and were free of diabetes before the infarction. The patients were participants in the Italian GISSI Prevention trial.
New-onset diabetes was defined as use of diabetes medication or a fasting glucose of 7 mmol/L or greater. Impaired fasting glucose was defined as a blood glucose level of 6.1 mmol/L or greater but less than 7, but it was also calculated on the basis of a lower blood glucose threshold of 5.6 mmol/L.
During follow up, 998 patients (12%) developed diabetes, and 2,514 (33%) developed diabetes or impaired fasting glucose, increasing to 62% using the lower cutoff threshold.
In contrast, contemporary population-based cohort studies of middle-aged white adults have shown diabetes rates of 0.8% to 1.6%, the authors stated. The incidence of new-onset impaired fasting glucose has been 1.8%, using a blood glucose range of 5.6 to 7.0 mmol/L.
New-onset diabetes and impaired fasting glucose increased the mortality risk in MI patients. As compared with patients who had a fasting glucose of less than 5.6 mmol/L, those with a glucose level of 5.6 to 6.05 mmol/L had a 10% greater mortality during follow-up.
A glucose level of 6.1 to 7 mmol/L increased the mortality risk by 15%, and development of frank diabetes raised the mortality risk by 44% (P<0.05 for trend).
In a multivariate analysis, independent predictors of diabetes and impaired fasting glucose were:
Older age (hazard ratio 1.07, P<0.001)
Higher body mass index (HR 1.09, P<0.001)
Hypertension (HR 1.22, P=0.003)
Current smoking (HR 1.60, P<0.001)
Use of beta-blockers (HR 1.27, P<0.001)
Use of lipid-lowering agents (HR 0.78, P=0.001)
Higher Mediterranean diet score (HR 0.65, P=0.002)
Independent predictors of diabetes but not IGF were inability to exercise (HR 2.43), use of diuretics (HR 1.15), and wine consumption exceeding 1 L per day (HR 1.45).
Further adjustment for baseline clinical variables revealed additional predictors of diabetes risk after MI: BMI gain during follow-up (HR 1.17), higher triglycerides (HR 1.61), lower HDL (HR 1.46), higher leukocyte count (HR 1.23), and higher consumption of butter and other oils (HR 1.26).
"These findings indicate that, just as diabetes can be considered a coronary heart disease risk-equivalent, acute myocardial infarction should potentially be considered a prediabetes risk-equivalent," the authors said.
Lifestyle modification could play a major role in reducing diabetes risk after MI, they continued. Obesity (as reflected by BMI), smoking, and lack of physical activity are major, modifiable contributors to diabetes risk.
In a commentary on the study, Lionel H. Opie, M.D., of the University of Cape Town, South Africa, said the findings "further tie the knot between myocardial infarction and hyperglycemia-each causes the other."
Offering a possible explanation for the link between MI and diabetes, he noted that blood glucose values of less than 5.6 mmol/L have prognostic value for diabetes.
"A reasonable hypothesis would be that the previous acute myocardial infarction was associated with an undetected modest, but definite tendency towards prediabetes at the time of the attack," said Dr. Opie.
The authors declared no conflicts of interest. The study was supported by the National Heart, Lung and Blood Institute.
Dr. Opie declared no conflict of interest.Primary source: The LancetSource reference: Mozaffarian D et al. "Incidence of new-onset diabetes and impaired fasting glucose in patients with recent myocardial infarction and the effects of clinical and lifestyle risk factors. Lancet 2007; 370: 667-675. Additional source: The LancetSource reference: Opie LH. "Acute myocardial infarction and diabetes." Lancet 2007; 370: 634-635.