Primary aldosteronism (PA) has a reported prevalence of up to 20% in cases of resistant hypertension1. Untreated PA poses a significantly greater risk of cardiovascular events than essential hypertension (EH)2. Ambulatory blood pressure (AMBP) monitoring provides a non-invasive method for evaluating circadian BP variations, offers valuable prognostic information3 and may distinguish PA from EH.
To compare AMBP parameters in patients with PA and EH, and correlate these parameters with cardiovascular outcomes in PA.
AMBP readings were evaluated retrospectively in 407 patients assessed at Monash Heart. Patient demographics, screening aldosterone and renin concentrations and medications were retrieved from medical records. 396 EH and 11 PA patients were identified and their cardiovascular events (myocardial infarction, left ventricular hypertrophy, coronary artery disease, atrial fibrillation) were recorded. Statistical significance was set at p<0.05.
Compared to EH, PA patients were younger (mean: 51.5±13.3 vs 62.2±14.2 years). Mean BP readings were higher in PA (mean: 150/86±20.5/7.4 vs 134/75±17.2/10.7 mmHg) and similar findings were observed for average daytime and nighttime BP readings. BP load (% daytime and nighttime SBP/DBP readings over 135/85 and 120/70 mmHg, respectively) was significantly higher for both systolic and diastolic in PA (mean: 72.4±26.4 and 50.2±25.6 %) compared with EH (mean: 49.3±28.5 and 21.6±22.7 %). 81% of patients with PA (9/11) had loss of physiological nocturnal BP dipping compared with 44% of EH (175/396). Rates of cardiovascular events were similar in both groups but may be confounded by the retrospective nature of this study and lack of long-term follow-up.
In our study, PA is associated with a significant increase in BP load and loss of nocturnal BP dipping which are known risk factors for adverse cardiovascular events. A prospective study is needed to better define AMBP parameters in PA and evaluate changes following treatment.