The purpose of this study is to determine if patients should stop taking their angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) around the time of their angiogram in order to prevent contrast induced nephropathy (CIN).

There are approximately 4000 coronary angiograms performed annually at the Hamilton General Hospital to diagnose and treat coronary artery disease. Many of the patients undergoing this procedure have mild kidney disease. Exposure to the contrast dye used in the procedure puts them at risk of worsening kidney function, a condition called contrast induced nephropathy (CIN) which is associated with significant morbidity and mortality. Many of these patients are also on an antihypertensive drug called an angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). Their effects on the kidney during contrast exposure are not known. Our understanding of how the drug works leads us to believe that the use of these drugs around the time of contrast exposure may have detrimental effects on the kidney.

The purpose of this study is to determine if patients should continue taking or stop taking their ACE inhibitor or ARB around the time of their angiogram in order to prevent CIN.

Patients undergoing an elective coronary angiogram with mild kidney disease and currently taking an ACE inhibitor or ARB will be randomly divided into two groups. One group will continue taking their ACE inhibitor or ARB while the other group will stop taking their ACE inhibitor or ARB for at least 24 hours before and will resume their ACE inhibitor or ARB 48 to 96 hours after their angiogram. In both groups, kidney function will be assessed by means of a simple blood test both before and 48 to 96 hours after the angiogram. By doing this, we can determine which group had more kidney damage and which group had less kidney damage from the contrast exposure. We suspect that patients who do not take their ACE inhibitor around the time of their angiogram will have less kidney damage. All patients will receive the accepted measures for preventing kidney disease from contrast dye exposure.

CIN is associated with significant morbidity and mortality. If the use of ACEIs during coronary angiograms are associated with an increased risk of CIN, then these patients may benefit from holding their ACEI around the time of their procedure potentially improving their outcomes. This is a low cost intervention that could potentially change practice, reduce morbidity, save lives and pave the way for larger clinical trials.

Inclusion Criteria:

• Scheduled for Angiography in >= 24hrs from enrolment
• Documented Cr >= 150 within 3 months before cardiac catheterization AND/OR documented Cr >= 132umol/L within 1 week Before Cardiac Catheterization
• Currently Taking an ACE Inhibitor

Exclusion Criteria:

• Patients with end stage renal disease (for example, patient on dialysis)
• Emergency Cardiac Catheterization with insufficient time to hold the ACEI
• Acute Pulmonary Edema