Chicago, IL - A quarter-century of autopsy data have shown an overall decline in the incidence of coronary disease and in average CAD-severity grade, independent of age and sex, but also signs that the downward trend in CAD grade may have reversed in the past decade [1].

"Our finding that temporal declines in the grade of CAD at autopsy have ended, together with suggestive evidence that declines have recently reversed, provides some of the first data to support increasing concerns that declines in heart-disease mortality may not continue," write Dr Peter N Nemetz (University of British Columbia, Vancouver) and colleagues in the February 11, 2008 Archives of Internal Medicine.

What caught our attention was the reversal or worsening of the grade of CAD after 2000, implying that the trend toward declining CAD prevalence is not just decelerating, it has already ended.

In their accompanying editorial [2], Drs S Jay Olshansky and Victoria Persky (University of Illinois, Chicago) are unsurprised by the observed overall decline in CAD grade, but "what caught our attention . . . was the reversal or worsening of the grade of CAD after 2000, implying that the trend toward declining CAD prevalence is not just decelerating, it has already ended. More important, what this observation may foretell is that in the coming decades the age at onset of CAD could shift to younger ages and the death rate rise."

Nemetz et al reviewed autopsy data, covering 1981 to 2004, from 425 persons who had died at ages 16 through 64 and for whom there were pathology records that allowed the grading of any CAD. The subjects had been residents of Olmstead County, Minnesota, home of the Mayo Clinic, where the autopsies were conducted.

In a twist that distinguishes the study from others looking at CAD trends in autopsy findings and that strengthens the results, according to the authors, the current cases were selected for having deaths that were "nonnatural," such as by accident or homicide, which tend not to be correlated with known CAD.

"High-grade" CAD, defined as >grade 4 in any major coronary artery (except >grade 3 in the left main), was documented in 8.2% of the 425 autopsies, with the prevalence declining over the years and with the drop steeper in males than in females and for persons who died at younger vs older ages. A grade of at least 4 corresponds to a coronary luminal narrowing of >75%; grade 3 corresponds to a narrowing of 51% to 75%.

The odds ratio for any CAD fell significantly throughout the entire 24-year period, increased significantly with age, and did not vary significantly by sex, according to the authors.

A similar pattern emerged for CAD grade. It declined significantly over time but rose significantly with age; however, overall CAD grade was significantly increased among men vs women, with left anterior-descending and left-circumflex artery disease accounting for most of the difference.

The results are alarming enough to alert public-health officials to begin monitoring younger cohorts for early signs of CAD with much greater vigilance.

An analysis of CAD-grade changes in different segments of time within the overall 24 years identified 1995 as the approximate turning point, when the declines started to bottom out, and indicates that CAD grade may have started to climb around the year 2000.

Still, the findings, "taken as a whole, reinforce the argument that four decades of declines in heart-disease mortality largely reflect reductions in disease incidence—that is, reductions in CAD incidence more than offset any rise in prevalence from improved survival among persons with CAD," the group concludes.

The study, observe Olshansky and Persky, "underscores the importance of focusing prevention efforts on lifestyle factors among younger generations." In addition, "it is . . . reasonable to hypothesize from the results of this research that CAD rates could rise among future cohorts of middle-aged and older persons."

Acknowledging that the Olmstead County sample was not broadly representative of the US and other limitations of the research, Olshansky and Persky conclude that, still, "the results are alarming enough to alert public-health officials to begin monitoring younger cohorts for early signs of CAD with much greater vigilance."