Effect of doxazosin on the left ventricular structure and function in morning hypertensive patients: The Japan Morning Surge 1 study

OBJECTIVES: Doxazosin is reported to increase the incidence of congestive heart failure. The benefits of doxazosin, for controlling morning blood pressure as well as its effect on the left ventricular structure and function, are herein examined. METHODS: In this study, 223 morning hypertensive patients were randomized into either the doxazosin group, with a once-daily bedtime dose of doxazosin, or the control group, who continued their current medication. Atenolol was added to the doxazosin group when needed. The effect of doxazosin was evaluated by measurement of echocardiographic parameters and B-type natriuretic peptide. RESULTS: The left ventricular wall thickness decreased, but the left ventricular diastolic diameter in the doxazosin group increased from the baseline. The changes in the left ventricular mass index were similar between the groups, whereas the relative wall thickness in the doxazosin group decreased more than that in the control group. The left ventricular diastolic function could deteriorate in the doxazosin group. In the doxazosin group, an increase in the left ventricular diameter was only seen in the patient who did not take diuretics throughout the study. The office and home blood pressure in the doxazosin group decreased more than that in the control group, whereas the B-type natriuretic peptide increased in the doxazosin group. Three cases of congestive heart failure were observed in the doxazosin group, but none in the control group. CONCLUSION: Although a bedtime dose of doxazosin can significantly lower the blood pressure, it can also increase left ventricular diameter, thus increasing the risk of congestive heart failure. However, the prior use of diuretics can prevent the unfavorable effects of doxazosin on the left ventricular structure.