Background: Obesity is a well-known condition of resistant hypertension (HT). Insights to the hemodynamic patterns that characterize obesity related hypertension may help guide therapeutic adjustments and shorten time to HT control.
Methods: We performed a retrospective analysis of 202 patients followed at our Hypertension Clinic with the diagnosis of primary HT and who performed an impedance cardiography (ICG) test. Obtained data was analyzed to identify differences between obese and non-obese patients and to identify predictors of uncontrolled HT (≥ 140 and/or ≥ 90 mmHg) in obese patients.
Results: One hundred patients were male (49.5%) and average age 54.6 ± 13.9 years. Average systolic and diastolic pressures were 136.5 ± 22.4 mmHg and 82.9 ± 5.1 mmHg, respectively. The average BMI was 28.9 ± 5.1 Kg/m2. Seventy one patients (35.1%) had systolic arterial pressure (AP) ≥140 mmHg and 45 patients (22.3%) diastolic AP ≥90 mmHg. BMI correlated with systolic and diastolic AP (Pearson’s coefficient 0.235; p < 0.001 and 0.163; p < 0.001, respectively). Obese patients presented increased cardiac index (CI) (p < 0.001), left cardiac work index (LCWI) (p < 0.001) and systemic vascular resistance index (SVRI) (p < 0.001) but reduced systemic arterial compliance index (SACI) (p < 0.001). Obese patients with uncontrolled HT had greater BMI (p < 0.001), CI (p < 0.001) and SVRI (p < 0.001) but lower SACI (p < 0.001) and LCWI (p < 0.001). In multivariate analysis, however, only CI remained predictive, conferring a risk 1.47 higher of uncontrolled HT.
Conclusions: Obese patients, including those with uncontrolled HT, had increased CI and SVRI. The only predictor of uncontrolled HT, however, was CI, suggesting that the obese present a state of hyperinotropy and may benefit of “add-on” or increase treatment with beta-blockers.
Keywords: Body mass index; Cardiac index; Hypertension; Impedance cardiography; Obesity; Systemic vascular resistance index.