Background: Prevalence of asymptomatic left ventricular systolic dysfunction (ALVSD) increases with age and cardiovascular (CV) risk exposure. Early diagnosis and treatment allow reducing heart failure and fatal and non-fatal event rates. Data on ALVSD prevalence in Italy are still scarce and ALVSD remains commonly under-diagnosed in primary care, where diagnostic facilities are limited. Among subjects at high CV risk in primary care, we assessed the prevalence of ALVSD and the relative predictive value of N-terminal pro-brain natriuretic peptide (NT-proBNP) and the Framingham Heart Failure Risk Score (FHFRS).
Methods: Records of 4047 subjects aged 55-80 years, without history, symptoms or signs of heart failure, registered at three primary care practices in Lombardy, Northern Italy, were reviewed; 623 subjects at high CV risk underwent visit, ECG, echocardiography, NT-proBNP and FHFRS calculation.
Results: ALVSD, defined as left ventricular ejection fraction <50%, was detected in 33 subjects (5.3%) who showed higher NT-proBNP (p<0.001) and FHFRS (p=0.013) than those without ALVSD. NT-proBNP levels beyond normal age and gender-specific 95th percentile had a 97.7% negative predictive value for ALVSD and were associated with a 6-fold increase in ALVSD risk. Adding NT-proBNP to FHFRS significantly improved prediction (C-statistic 0.76, 95% confidence interval [CI] 0.67-0.84 vs 0.63, 95% CI 0.53-0.73, p=0.04; net reclassification improvement 38.4%). The combination of FHFRS and major ECG abnormalities was not superior to stand alone NT-proBNP (C-statistic 0.71, 95% CI 0.63-0.80 vs 0.74, 95% CI 0.64-0.83, p=0.61).
Conclusions: In subjects at high CV risk in primary care, prevalence of ALVSD is 5.3%; for diagnosis NT-proBNP adds predictive value to the FHFRS and is equivalent to the combination of FHFRS and ECG. Because of its practical advantages, NT-proBNP might be routinely used for ALVSD screening in primary care.