Interamerican Society of Cardiology (IASC) position statement: Chlorthalidone vs. thiazide-type diuretics

[Cardiovascular preventive recommendations. PAPPS 2024 thematic updates]

The recommendations of the semFYC's Program for Preventive Activities and Health Promotion (PAPPS) for the prevention of vascular diseases (VD) are presented. New in this edition are new sections such as obesity, chronic kidney disease and metabolic hepatic steatosis, as well as a 'Don't Do' section in the different pathologies treated. The sections have been updated: epidemiological review, where the current morbidity and mortality of CVD in Spain and its evolution as well as the main risk factors are described; vascular risk (VR) and recommendations for the calculation of CV risk; main risk factors such as arterial hypertension, dyslipidemia and diabetes mellitus, describing the method for their diagnosis, therapeutic objectives and recommendations for lifestyle measures and pharmacological treatment; indications for antiplatelet therapy, and recommendations for screening of atrial fibrillation, and recommendations for management of chronic conditions. The quality of testing and the strength of the recommendation are included in the main recommendations.

Chlorthalidone versus hydrochlorothiazide: major cardiovascular events, blood pressure, left ventricular mass, and adverse effects

BACKGROUND

There is continuous debate whether chlorthalidone (CTD) and hydrochlorothiazide (HCTZ) differ in reducing major cardiovascular events (MACE). HCTZ is prescribed 10 times more commonly than CTD.

METHOD

A systematic literature search yielded 14 references, including two network meta-analyses of randomized trials with MACE and left ventricular mass as outcomes.

RESULTS

The network meta-analysis of randomized trials showed CTD reducing MACE more than HCTZ, hazard ratio = 0.79 (0.72-0.88), P < 0.0001, and an observational cohort study gave an identical point estimate: hazard ratio = 0.79 (0.68-0.92), P = 0.002. In contrast, two observational cohort studies reported no differences between CTD and HCTZ. However, in the studies showing the superiority of CTD median follow-up was 4.3 and 7.0 years, respectively, whereas in the latter studies showing no difference between the two drugs follow-up was only 0.95 and 0.25 years. As differences in outcomes for MACE in hypertension trials with various interventions only emerge after prolonged (>1 year) therapy, differences in follow-up explain these discrepant results. CTD also more effectively reduced left ventricular mass in observational data and network analysis of trials. These advantages of CTD over HCTZ are consistent with greater reductions in night-time blood pressure, greater reductions in oxidative stress and platelet aggregation, and greater improvements in endothelial function.

CONCLUSION

Over the short-term there were no differences in the net clinical benefit between HCTZ and CTD. However, long-term available data document CTD to be significantly more effective in reducing MACE than HCTZ. The Veterans Administration's trial in progress may provide definitive answer to these questions.