Viewing Cardiovascular Research Through the Eyes of Past, Present, and Future Generations

Abstract

WILLIAM HARVEY, THE 17TH-CENTURY ENGLISH physician who first correctly described how the heart pumped blood around the body, was quoted as saying, “All we know is still infinitely less than all that remains unknown.” To his credit and humility, he understood that his work only set the stage for many discoveries yet to come. All physicians could learn important lessons from Harvey. Looking back to past research can provide interesting insights into how the field of cardiovascular medicine got to where it is and also important hints on where it may be going. Yet historical reviews can also be humbling, demonstrating how prior generations had inaccurately interpreted their findings and in other cases, how slow clinicians have been in adopting past advances. It is therefore appropriate that JAMA’s 2012 cardiovascular disease theme issue includes “The Resuscitation of the Heart,” an editorial originally published 100 years ago. The article describes how experiments using cardiac massage and electrical stimulation in dogs had shown promise in bringing animals back from the dead. The results seemed miraculous to the authors owing to their rudimentary understanding of cardiac physiology, yet they still foresaw the future of cardiopulmonary resuscitation (CPR) and cardiac defibrillator therapy in humans. It would be another 35 years, however, before the first successful defibrillation of an exposed human heart was performed; another 45 years until the first closed chest cardiac defibrillators came to routine use; and nearly 70 years until the first implantable defibrillator device would reach the market. Perhaps most concerning, even today, only a small proportion of the US population has received CPR training, cardiac defibrillator response time even in hospitals is far from ideal, and only up to two-thirds of patients eligible for an implantable defibrillator actually receive the device. Certainly in these cases, the translation of experimental concepts to routine cardiology practice has been less than ideal in these cases. In this theme issue of JAMA, readers can view some of the latest contemporary cardiovascular discoveries. Three epidemiological studies examine the prevalence of cardiac risk factors and their association with clinical events in various populations. It may seem remarkable that more than 50 years after the basic cardiac risk factors were first described there is more to say, yet each of these latest contributions provides important, novel insights. In one report, Wilkins and colleagues use nearly 1 million person-years of follow-up data from large cohort studies to estimate lifetime risk of cardiovascular disease (CVD). Their study found that the lifetime odds for CVD are proportional to the number of cardiac risk factors. Importantly, those with an “optimal” risk factor profile at midlife have a several-fold lower lifetime likelihood for cardiac events compared with those with multiple risk factors. Many of the major cardiac cohort studies to date were conducted in predominantly white populations, and they thus fail to reflect the racial and ethnic diversity of the United States. Studying a broad, racially diverse cohort, Safford and colleagues address this epidemiological gap and find that both black men and black women have a nearly 2-fold higher risk for fatal cardiac events relative to their white peers. However, the study also points out that these differences reflect the high burden of cardiac risk factors seen in black patients. An additional article by Daviglus and colleagues identifies similar issues among those of Hispanic origin. This report is the first major publication from the Hispanic Community Health Study/Study of Latinos, a very large National Institutes of Health–sponsored initiative to characterize CVD in diverse US Latino populations. The researchers note the high burden of cardiac risk factors in Latino populations, particularly among those of Puerto Rican origin, lower socioeconomic background, and more acculturation into the US lifestyle. Taken together, these 3 articles highlight the pressing need (and incredible opportunity) for primary and secondary prevention interventions to reduce CVD death and disability among all racial/ethnic groups in the United States. Beyond epidemiology, cardiovascular medicine also advances through direct human experimentation. Randomized clinical trials (RCTs) provide ideal tools to confirm (or