Editor,—There are limitations to the use of increases in serum creatinine as a marker indicative of early postoperative death,1, not least because derangement in this parameter may have more to do with injudicious diuretic dosage in the presence of the unique co-existence of diastolic left ventricular failure and left ventricular outflow obstruction. The use of diuretics for antifailure treatment may, in this context (as in other conditions characterised by diastolic failure), impair the left ventricular filling to such an extent as to precipitate a low output state,2 one consequence being the development of prerenal uraemia. Therefore, if anything, the onset of deterioration in renal function should initiate a shift from medical treatment to surgical intervention, coupled with an interim reduction in diuretic dosage. Surprisingly, notwithstanding the acknowledgement of the existence of an aortic stenosis related syndrome of low output failure (characterised by pronounced fatigue and debilitation),3there is little or no documentation that one of its manifestations could be the syndrome of “aggravated renal dysfunction during intensive treatment for advanced chronic heart failure”.4