The aim of this study is to estimate the effect of discontinuation of RAS inhibitors on myocardial injury in cancer patients undergoing major abdominal surgeries.

This is a prospective, open-label, randomized controlled non inferiority trial. Participants will be assigned randomly in a 1:1 manner whether to stop or continue RAS inhibitors. Randomization will be performed using an online program (www.randomizer.com).

Trial participants and staff will not be blinded to treatment group allocation however, all investigators will be blinded to the primary outcome measure (myocardial injury).

After randomization during the preoperative visit, participants will be instructed to stop or continue their ACE-I and/or ARB according to their allocated group. ACE-I and/or ARB will be continued or discontinued as per treatment group allocation and this will continue until 24 hours after the end of surgery. Since ACE-I and ARB have different durations of action, participants will receive drug-specific instructions as to when to stop. When the ACE-I and/or ARB duration of action is ≥24 hours, the drug will be stopped 48 hours prior to surgery. All other ACE-I and/or ARB will be stopped 24 hours before surgery. Renin-angiotensin system inhibitors will be restarted after surgery on the morning of post-operative day one if systolic blood pressure was >120 mmHg in the previous 12 hours.

The anesthetic induction, intraoperative and postoperative management will be managed according to the local policy of the NCI by expert anesthesiologists who will be blinded to the patients' groups.

Troponin-I will be measured at 9 a.m. on the day before surgery and at 9 a.m. on postoperative day one and day two. Myocardial injury will be defined as: (Troponin-I an increase by 0.015 is considered positive, if the baseline is <0.05 A. If the baseline is higher than 0.05, an increase by 0.005 is considered positive).

Inclusion Criteria:

• Age > 18 years
• Both sexes
• ASA 2-3
• Chronic hypertensive patients (> 3 months before surgery) controlled on ACEIs or ARBs or combination therapy containing one of the RAS inhibitors.
• Scheduled for major abdominal cancer surgery (surgery with an expected duration of > 2 h from the surgical incision and a postoperative hospital stay of least three days).

Exclusion Criteria:

• Patient refusal.
• Recent myocardial infarction (within 3 months).
• Any condition, which in the opinion of the treating clinician, would result in the patient being harmed by the cessation of the ACE-I and/or ARB therapy.
• Emergency surgery

Trial participants and staff will not be blinded to treatment group allocation however, all investigators will be blinded to the primary outcome measure (myocardial injury).