Study of the Vascular Effects of Serelaxin

Inclusion Criteria: * Male and female patients ≥18 years of age, with body weight \<160 kg. * Patients with proven obstructive coronary artery disease, determined either by functional (e.g. treadmill testing) or non-invasive clinical imaging assessments (e.g. stress-echo, PET or SPECT myocardial perfusion), or invasive coronary angiography or by CT coronary angiography at any point in time in patients with or without mild left ventricular systolic dysfunction (LVSD) Exclusion Criteria: * Previous treatment with serelaxin (also known as: RLX030, relaxin) * Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they are using highly effective methods of contraception during dosing of study treatment. * Current or planned dialysis. * Impaired renal function during screening defined as an estimated glomerular filtration rate (eGFR) at screening and prior to treatment of \<30 mL/min/1.73 m2, calculated using the simplified Modification of Diet in Renal Disease (sMDRD) equation due to potential issue with administration of GdDTPA used as the MRI contrast agent. * Sick-Sinus-Syndrome * Current or history of pulmonary edema, including suspected sepsis. * restrictive, or constrictive cardiomyopathy (does not include restrictive mitral filling patterns seen on Doppler echocardiographic assessments of diastolic function) * Known significant valvular disease (including any of the following: severe aortic stenosis \[AVA \< 1.0 or peak gradient \> 50 on prior or current echocardiogram\], severe aortic regurgitation, or severe mitral stenosis). * Clinical diagnosis of acute coronary syndrome (ACS) including unstable angina within 30 days prior to screening as determined by both clinical and enzymatic criteria * Troponin elevation and dynamics indicative of ACS at any time between screening and randomization. * Previous myocardial infarction within 3 months of screening * History of Coronary Artery Bypass Graft (CABG) surgery * Heart failure due to significant arrhythmias (including any of the following: ventricular tachycardia, bradyarrhythmias with ventricular rate \< 45 beats per minute or any second or third degree AV block or atrial fibrillation/flutter with ventricular response of \> 120 beats per minute) * Any surgical or medical condition which in the opinion of the investigator may place the patient at higher risk from his/her participation in the study (e.g., history of poor tolerance of adenosine or 3 vessel coronary disease) * Acute myocarditis or hypertrophic obstructive, restrictive, or constrictive cardiomyopathy (does not include restrictive mitral filling patterns seen on Doppler echocardiographic assessments of diastolic function).