One of the most common and difficult to manage problems arising during the initial treatment of people with acute heart failure is an inadequate response to intravenous diuretic therapy. This frequently leads to a prolonged inpatient stay and is associated with higher inpatient mortality and higher post-discharge mortality and re-admission rates. The best treatment for this problem is unknown. However, there is some inconsistent and non-robust evidence that addition of a thiazide or thiazide-like diuretic (metolazone) may be beneficial. The proposed study would aim to resolve this uncertainty and guide the management of a difficult clinical problem. 2.3 Intra-aortic balloon counter-pulsation In people with acute heart failure and hypoperfusion syndrome, is the use of intra-aortic balloon counter-pulsation pump (IABP) better than the use of intravenous inotropes? Why this is important A randomised controlled trial should be conducted in people with decompensated heart failure due to left ventricular systolic dysfunction and systemic hypoperfusion comparing the use of IABP with the use of inotropes/vasopressors. This would determine which strategy is more clinically and cost effective in this cohort. IABP is used in the hospital setting as an adjuvant in people with critical coronary ischaemia and in people with mechanical complications of acute myocardial infarction. It has also been used in people who develop cardiogenic shock after acute myocardial infarction. However, it is uncertain whether it can provide clinical benefit in the critically unwell patients with acute heart failure due to left ventricular systolic dysfunction and systemic hypoperfusion. In people with decompensated heart failure, fluid congestion and diuretic resistance, does ultrafiltration lead to more rapid and effective decongestion compared with continuing diuretic treatment? 