Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Survival after diagnosis of idiopathic dilated cardiomyopathy

ACP J Club. 1993 Jan-Feb;118:19. doi:10.7326/ACPJC-1993-118-1-019


Source Citation

Sugrue DD, Rodeheffer RJ, Codd MB, et al. The clinical course of idiopathic dilated cardiomyopathy. A population-based study. Ann Intern Med. Jul


Abstract

Objective

To describe the prognosis of patients with idiopathic dilated cardiomyopathy in the general population and to compare their survival with that of patients referred to a specialist center a decade earlier.

Design

Comprehensive inpatient and outpatient records for residents of Olmstead County, Minnesota, for 1975 to 1984 were compared with those of patients referred to the Mayo Clinic in 1960 to 1973.

Setting

A Minnesota county (population 90 000) and a referral center within it.

Patients

In the community cohort, 40 county residents (median age at diagnosis 49 y, 28 men) had idiopathic dilated cardiomyopathy, defined as global ventricular dilatation with impaired systolic function (determined by echocardiography, angiography, or both), without a known cause and with or without heart failure. Recent immigrants and 4 cases first diagnosed at autopsy were excluded. In the referred cohort, 104 patients (median age 49 y) had ≥ 2 of symptoms or signs of heart failure, cardiothoracic ratio > 0.5 on chest radiograph, electrocardiographic evidence of conduction abnormality, or a history of systemic emboli.

Assessment of prognostic factors

Clinical, medication, and family history were obtained from medical records. Functional status was assigned by New York Heart Association (NYHA) classification.

Main outcome measures

1- and 5-year survival.

Main results

In the community cohort, 33 of 40 members (83%) had ≥ 2 symptoms at diagnosis; 26 of 29 with symptomatic heart failure were NYHA class III or IV. 5 persons were asymptomatic before diagnosis. Although the community cohort had a lower survival rate than age- and sex-matched community controls (58% vs. 83%, respectively; P < 0.001), it had a higher survival rate than the referred cohort. 1-year survival was 95% for the community cohort and 69% for the referred cohort. 5-year survival was 80% and 36%, respectively (P < 0.001 for both comparisons). Most of these differences in mor-tality occurred during the first 3 years of follow-up. Older age and lower left ventricular ejection fraction were independent predictors of death (P = 0.02 and P = 0.03,respectively), and every 10% decrease in ejection fraction corresponded with a 90% increase in the risk for death.

Conclusion

The prognosis of patients with idiopathic dilated cardiomyopathy in the community at large, although worse than that of their fellow citizens, was better than that described at tertiary referral centers.

Source of funding: National Institutes of Health.

For article reprint: Dr. B.J. Gersh, Division of Cardiovascular Diseases, Mayo Clinic, 200 S.W. First Street, Rochester, MN 55905, USA. FAX 507-284-0161.


Commentary

The study by Sugrue and colleagues showed a better prognosis for patients with idiopathic dilated cardiomyopathy detected in a community setting than in referral practices a decade earlier. These results are not surprising because most studies of serious illness have found that referred patients have a worse prognosis—they are referred for a reason. Although these results should be heartening for practitioners making a new diagnosis of idiopathic dilated cardiomyopathy, enthusiasm should be tempered by the realization that the mortality of patients in the community-based cohort was 45% at 8 years of follow-up (and this excluded 4 patients diagnosed at autopsy) and that the referred cohort was historical.

Five issues deserve emphasis from the practitioner's point of view. First is the importance of thorough diagnostic evaluation. The results of this study apply only to patients without coronary disease or hypertension as the cause of cardiomyopathy. Clinicians should carefully evaluate all patients with cardiomyopathy for ischemia, particularly because evidence is increasing that symptomatic ischemic heart disease with left ventricular dysfunction can be treated with revascularization. Second, in the absence of a strong contraindication, patients with atrial fibrillation and cardiomyopathy should receive anticoagulation agents. The proper treatment of patients with sinus rhythm remains unsettled, although many experts have advocated anticoagulation of these patients also. Third, the importance of age and extent of left ventricular dysfunction as prognostic factors was again confirmed. Thus, in advising the individual patient about what to expect, the practitioner must consider more than the general diagnosis. Fourth, patients who survive often improve; so hope can be extended to patients in the crucial early phase after diagnosis is made. Finally, the authors correctly point out that angiotensin-converting enzyme (ACE) inhibitors were not used frequently during the years of this study. ACE inhibition should be paramount in the therapy of any patient with severe left ventricular dysfunction and symptoms of heart failure.

Robert M. Califf, MD
Duke University Durham, North Carolina, USA