In hypertrophic cardiomyopathy, why are diuretics not recommended?

In hypertrophic cardiomyopathy (HCM), diuretics are not recommended because they exacerbate symptoms by decreasing ventricular volume. In HCM, there is a thickening of the heart muscle, particularly affecting the ventricles. This alteration can lead to outflow obstruction and compromises the heart's ability to fill properly. When diuretics are administered, they reduce the overall blood volume, which in turn can lower the ventricular filling pressures. This may lead to a decrease in stroke volume and can worsen the outflow obstruction, causing increased symptoms such as dyspnea and fatigue.

The condition already places patients at risk for adverse effects related to dynamic obstruction, and reducing ventricular volume with diuretics can significantly impair cardiac output. Therefore, instead of providing benefit, diuretics can lead to a more pronounced clinical deterioration in patients with HCM by worsening hemodynamic status.

In summary, the primary concern with diuretic use in hypertrophic cardiomyopathy stems from their potential to lower ventricular volume, which aggravates the flow dynamics and increases symptom severity in patients suffering from the condition.