Left Ventricular Diastolic Dysfunction In ‘Non-Cardiac’ Critical Illness: Application Of Transthoracic Echocardiography And Plasma B-Type Natriuretic Peptide Concentration

Abstract

Aims: Left ventricular (LV) filling and thus diastolic function, are frequently monitored and managed in critical care. However, scant data exist regarding the diagnosis and prevalence of diastolic dysfunction in the intensive care unit (ICU). The present study aimed to apply recent EAE/ASE recommendations for transthoracic echocardiographic (TTE) evaluation of LV diastolic function to a cohort of patients in a multidisciplinary (except cardiac surgery) Australian ICU. An additional aim was to evaluate plasma B-type natriuretic peptide (BNP) as a marker of diastolic dysfunction, thus abnormal baseline renal function was excluded. Methods and Results: Clinical data were recorded over the first 24 h of ICU for 32 consecutive patients. TTE and blood collection for BNP assay were then performed. Diastolic dysfunction was demonstrated in 50% (n = 16). Mean ± SD BNP values were higher with diastolic dysfunction (180.8 ± 183 pg/ml vs. 77.8 ± 87; p = 0.038). Best discrimination was achieved at BNP > 43 pg/ml, yielding sensitivity 87.5% and specificity 56.3%; ROC area under curve was 0.715. log BNP correlated independently with log E/e′ (R2 = 0.14, p = 0.02) (E/e′: peak early transmitral velocity (E)/early diastolic mitral annular velocity (e′)) but not LV ejection fraction (p = 0.30), illness severity (APACHE2; p = 0.58) or fluid balance (p = 0.85). Conclusion: Diastolic dysfunction was prevalent in this cohort of ‘non-cardiac’ ICU patients and was associated with significantly higher BNP. Increased BNP was partially explained by higher LV filling pressure (E/e′). The optimal threshold of BNP as a marker of diastolic dysfunction in this cohort was lower than that previously proposed for heart failure.