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Does chronic treatment with calcium entry blocking drugs reduce perioperative myocardial ischemia?
1Division of Cardiovascular Anesthesiology, Texas Heart Institute, Houston 77025.
Insights
Beta-adrenergic blocking drugs significantly reduced perioperative myocardial ischemia in coronary artery bypass patients, unlike calcium entry blockers. Beta-blockers helped prevent tachycardia, a key factor in ischemia development.
Area of Science:
- Cardiology
- Anesthesiology
- Pharmacology
Background:
- Perioperative myocardial ischemia is a significant risk in coronary artery bypass surgery.
- The role of chronic calcium entry blockers in preventing perioperative ischemia is not well-defined.
- Hemodynamically unrelated ischemia is a common occurrence during the perioperative period.
Purpose of the Study:
- To investigate the effect of chronic calcium entry blocker administration on perioperative myocardial ischemia.
- To specifically assess the frequency of hemodynamically unrelated ischemia in patients on calcium entry blockers.
- To compare the incidence of ischemia in patients receiving different combinations of calcium entry blockers and beta-adrenergic blockers.
Main Methods:
- A study of 444 patients undergoing coronary artery bypass operations.
- Patients were categorized based on chronic medication: calcium entry blockers, calcium entry and beta-adrenergic blockers, beta-adrenergic blockers only, or neither.
- Nifedipine or diltiazem was administered before anesthesia induction in some groups.
Main Results:
- Overall, 46.8% of patients experienced new ischemia.
- Two-thirds of ischemia was not related to heart rate or blood pressure extremes and was not less frequent in calcium entry blocker users.
- Beta-adrenergic blocking drugs reduced ischemia frequency (34% vs. 53%) by mitigating tachycardia.
Conclusions:
- Chronic calcium entry blockers did not reduce perioperative myocardial ischemia or hemodynamically unrelated ischemia.
- Beta-adrenergic blocking drugs were associated with a lower incidence of ischemia, primarily by controlling heart rate.
- Patients on calcium entry blockers alone showed no difference in ischemia incidence compared to those on no antianginal therapy.
Abstract:
To examine the role of chronic calcium entry blocking drug administration on perioperative myocardial ischemia and, specifically, the frequency of hemodynamically unrelated ischemia, the authors studied 444 patients undergoing coronary artery bypass operations. Before induction of anesthesia, 119 patients who chronically took calcium entry blocking drugs received nifedipine 20 mg or diltiazem 60 mg orally, 74 received calcium entry and beta adrenergic blocking drugs, 71 received beta blocking drugs only, and 180 received neither. New ischemia occurred in 208 (46.8%) patients; 55 at arrival to the operating room, 86 only after induction, and 67 separately during both periods. Two-thirds of all ischemia was not related to extremes of heart rate or blood pressure; this type was not less frequent in patients receiving calcium entry blocking drugs. Ischemia did occur less frequently in the two patient groups receiving beta adrenergic blocking drugs (34% vs. 53%), a result of less tachycardia both on arrival (3.4% vs. 15.4%) and during anesthesia, when peak heart rate exceeded 109 bpm in only one of 145 beta-blocked patients compared to 29 of 299 not receiving beta blocking drugs. While ischemia appeared during anesthesia in 34.5% of all patients, its incidence was doubled (63%) when heart rate was greater than or equal to 110 bpm. At lower heart rates, the incidence of ischemia did not differ among groups. With respect to all types of ischemia, patients receiving calcium entry blocking drugs only were indistinguishable from those receiving no antianginal therapy.(ABSTRACT TRUNCATED AT 250 WORDS)