Abstract
BACKGROUND: Cardiac sarcoidosis (CS) is a rare but potentially fatal inflammatory cardiomyopathy. OBJECTIVES: The authors studied temporal changes in the incidence, characteristics, and outcome of CS. METHODS: A retrospective analysis was made of a 30-year nationwide cohort of CS. RESULTS: The cohort comprised 511 patients with a median age of 52 years and female preponderance (69%). Altogether 77, 166, and 268 cases of CS were diagnosed in years 1988 to 2009, 2010 to 2014, and 2015 to 2019, respectively; the 5-year count of 2015 to 2019 was 134-fold the count of 1990 to 1994 (268/2) and 18-fold the count of 2000 to 2004 (268/15). Prior to 2010, compared with the later periods, CS presented more often with ventricular tachycardia/fibrillation (prevalence 36% vs 19% in 2010-2014 and 11% in 2015-2019, P < 0.001), left ventricular ejection fraction <50% (49%, 35%, and 31%; P = 0.010), and elevation of natriuretic peptides (87%, 57%, and 49%; P < 0.001). On magnetic resonance imaging, late gadolinium enhancement involved a median of 15% (IQR: 11%-22%) of left ventricular mass in studies of 1988 to 2009 (n = 16), 15% (IQR: 9%-22%) in studies of 2010 to 2014 (n = 87), and 11% (IQR: 5%-19%) in studies of 2015 to 2019 (n = 150) (P = 0.031). The respective 5-year incidences of the composite of death, heart transplantation, left ventricular-assisted device implantation, or ventricular tachyarrhythmia were 40% (95% CI: 29%-51%), 32% (95% CI: 25%-39%), and 23% (95% CI: 16%-30%) (P = 0.002). The prognostic trend disappeared after adjustment for differences in the presenting phenotype. CONCLUSIONS: Diagnoses of incident CS have increased exponentially in Finland. Concurrently, the phenotype has turned milder and prognosis better, suggesting detection of CS at an earlier stage of its course.