ABSTRACT
BACKGROUND: Pressure/volume (P/V) loops provide useful information on left ventricular performance and prognosis in patients with heart failure (HF) but do not lend themselves to routine clinical practice. The authors developed a noninvasive method to compute individualized P/V loops to predict adverse clinical outcomes in patients with stable HF, which the authors believe can be used clinically. METHODS: A derivation cohort (n = 443 patients) was used to develop an echocardiography P/V loop model, using brachial arterial pressure and trans-thoracic two-dimensional Doppler echocardiographic data. Each patient's P/V loop was depicted as an irregular pentagon, and a centroid was derived for each loop. The centroid distance (CD) from a reference centroid (derived from 101 healthy control subjects) was computed. This model was prospectively applied to 435 patients who constituted the validation cohort. The study end point was a composite of cardiac death or hospitalization for HF among study patients. RESULTS: In the derivation cohort, CD was threefold greater among patients who experienced adverse events than those who did not. During a follow-up period of 30 months (15-45 months), event rates were 35% (72 of 206 patients) and 12% (29 of 237 patients P < .001), respectively, among patients with CD > 33 mL/mm Hg and those with CD ≤33 mL/mm Hg (prognostic cutoff derived by receiver operating characteristic analysis). Multivariate Cox analysis identified CD as an independent predictor of adverse outcome (hazard ratio, 1.61; 95% CI, 1.03-2.50) independently of left ventricular end-diastolic volume, pulmonary capillary wedge pressure, and left ventricular ejection fraction. These conclusions were confirmed in the validation cohort. CONCLUSIONS: The authors propose a method to create a noninvasive P/V loop and its centroid. These data provide useful pathophysiologic and prognostic information in patients with HF.
