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The Artificial Heart: Prototypes, Policies, and Patients
were sudden, which was defined as death within one hour in patients who were clinically stable (Kannel et al., 1988). Francis (1986) reviewed the incidence of sudden death in patients with CHF in 12 published reports and found that 8 cited sudden death rates of between 43 and 63 percent. Of 642 men with moderate failure (New York Heart Association Classes II and III) in the Veterans Administration Cooperative Study on Vasodilator Therapy of Heart Failure, 45 percent died suddenly (Cohn et al., 1986). Application of these percentages to the 42,940 CHF deaths in 1988 reveals that between 15,888 (0.37 × 42,940) and 25,764 (0.60 × 42,940) people did not die suddenly. This group could have benefited from MCSS.
The presence of medical and psychosocial comorbidities would likely preclude MCSS use in some of these individuals. Data, however, are not available regarding the presence of comorbid illness in individuals with end-stage heart failure. A very approximate estimate of the prevalence of comorbid conditions can be derived from the population-based study conducted by Kottke and associates (1990). In their attempt to estimate the need for long-term MCSSs, they reviewed all deaths in a five-year period in Olmsted County, Minnesota, using restrictive criteria for comorbid conditions, as well as age and time elapsed between onset of symptoms and death. They found that of the 248 people age 15 to 69 years old who died of cardiac disease, 52 percent died so quickly that intervention with an MCSS was not possible, 14 percent had comorbid conditions that would prevent them from benefiting from a device, and 20 percent died suddenly and had comorbidity. This left 35 individuals (14 percent) who were considered to be candidates for cardiac replacement.
Kottke and colleagues projected that there would be 16,500 potential candidates for cardiac replacement nationally each year. This estimate was based on assumptions that the 95,000 residents of Olmsted County were representative of all Americans, and that the population of the United States was 225 million at the time of the study, calendar years 1979 through 1983. Extrapolating the estimate based on the 35 candidates over five years yields approximately 16,500 annually.
With caution, the figure of 14 percent can be applied to the 42,940 CHF deaths to estimate the number of potential candidates for MCSS. This calculation reveals that 6,012 individuals per year may have benefited from these devices. This, however, may be misleading because only 31 percent of the Olmsted County deaths were attributed to chronic heart failure, whereas 54 percent were related to acute myocardial infarction (MI). The authors are not explicit in defining the diagnostic criteria for these conditions. They do, however, state that all of the 35 people designated as potential candidates for cardiac replacement had “severe depression of left ventricular function.” Acute MI, chronic heart failure, inability to wean from cardiopulmonary bypass, idiopathic cardiomyopathy, and cardiac tu-