Left Ventricular Pressure as a Treatment Target in Patients with Myocardial Infarction.

There is observational evidence that patients with high left ventricular end diastolic pressure (LVEDP) post ST-segment elevation myocardial infarction (STEMI) have higher mortality and re-admission rates but there are no prospective studies that have targeted LVEDP reduction after opening the infarct related artery. In order to design a prospective trial with LVEDP as the treatment target, dose of nitrates needs to be calculated that can cause a reasonable reduction in LVEDP without causing a significant drop in the systemic blood pressure. Thus, the aim of this acute hemodynamic study is to find a dose of nitrate in conjunction with a single bolus of frusemide that reduces LVEDP without causing symptomatic drop in the systemic blood pressure. We aim to enroll 20 patients in our study (Intervention group=10, Control group=10). All patients will have left heart catheterization performed and LVEDP measured immediately after primary percutaneous coronary intervention (PCI) as is standard practice in our institution. Patients with LVEDP greater than 20 mmHg will be enrolled to our study. The patients in the intervention arm will have intravenous administration of frusemide 40mg bolus plus escalating doses of IV glyceryl trinitrate (GTN) during simultaneous measurement of pressure in their left ventricular cavity. We will administer 100mcg GTN intravenously and administer further 100mcg boluses each minute to a maximum of 1000mcg. The study will terminate when there is a drop in either arterial pressure or LVEDP by 20% or if 1000 mcg is reached (over 10 mins) without any demonstrable effect on LVEDP or systemic blood pressure. We will also perform echocardiogram simultaneously and measure mitral inflow pulse wave Doppler, mitral annular velocities (E/E' ratios), pulmonary venous pulse wave Doppler and pulmonary artery systolic pressures at baseline and after the last dose of GTN.