To the Editor:—

We read with great interest the article on analysis of risk factors for myocardial infarction and cardiac mortality by Sprung et al.  1Some statements however, need clarification.

The reported overall incidence of perioperative myocardial infarction (PMI) in this high-risk population is extremely low (1.54%). In contrast, Badner et al.  2found the incidence of PMI to be more than 3.5 times higher (5.6%). Sprung identified PMI by clinical symptoms, creatine kinase–myocardial band increases, or diagnosis of new Q waves on the electrocardiogram. Badner et al.  2additionally determined troponin concentrations. He also found that PMI was an early event only occasionally associated with chest pain and usually non–Q wave in nature. This clearly shows that the incidence of PMI reported by Sprung et al.  1was underestimated, and that the results should be interpreted with caution.

General anesthesia was associated with a significantly greater risk of PMI. 1Does this mean that regional anesthesia in these high-risk patients resulted in significantly lower incidence of PMI? Was there any difference in postoperative pain therapy between groups? For more than a decade, there has been an ongoing discussion of whether general or regional anesthesia is more beneficial in patients at increased cardiac risk. In 1996, an editorial stated that no more studies were needed to answer this question 3because the largest study at the time showed no difference in outcome. 4A retrospective analysis comparing the effects of general and regional anesthesia on outcome in patients with hip fracture repair also showed no significant difference in PMI. However, use of general anesthesia decreased from 95% in 1981 to 47% in 1993. 5The reasons for enhanced employment of regional anesthesia could not be determined, but it was shown that “sicker” patients were allocated to the regional group. It would be interesting if Dr. Sprung et al.  1could add valuable data to this debate.

Patients with β-blocker therapy were more likely to experience PMI. 1The authors speculated that this surprising finding was because intraoperative extremes of heart rate did not differ between groups. β Blockers have been shown to prevent PMI and improve long-term survival after noncardiac surgery. 6However, it should be stressed that intraoperative and postoperative lower heart rates (below 80 beats/min) are the key to successful treatment with β blockers. This has been shown by Poldermans et al.  7who evaluated the effect of bisoprolol in a group of patients with positive dobutamine echocardiography results who were scheduled to undergo major vascular surgery. In the bisoprolol group, 3.4% of patients died of cardiac causes, compared with 17% of patients in the standard care group (P = 0.02). Nonfatal myocardial infarction occurred in 17% of patients given standard care only and in none of those to whom bisoprolol was administered (P = 0.001). Mean heart rates in the bisoprolol group were significantly lower than in standard care patients. An accompanying editorial stated that it seems likely that the cumulative morbidity resulting from three sequential procedures (angiography, revascularization, major vascular procedure) would be higher than the 3.4% rate of major cardiac complications in bisoprolol patients. 8 

Recent percutaneous transluminal coronary angioplasty (PTCA) was not cardioprotective in regard to reinfarction rate; however, it significantly prevented death after PMI evolved. 1The only patient with PTCA who died had undergone PTCA more than 12 months before surgery. These data are not in accordance with a study from Posner et al. , 9who demonstrated a significantly higher incidence of PMI after noncardiac surgery if PTCA was performed less than 3 months before surgery. Therefore, it would be interesting if Dr. Sprung et al.  1could determine the exact time when PTCA was undertaken.

Sprung J, Abdelmalak B, Gottlieb A, Mayhew C, Hammel J, Levy PJ, O’Hara P, Hertzer NR: Analysis of risk factors for myocardial infarction and cardiac mortality after major vascular surgery. A nesthesiology 2000; 93: 129–40
Badner NH, Knill RL, Brown JE, Novick TV, Gelb AW: Myocardial infarction after noncardiac surgery. A nesthesiology 1998; 88: 572–8
Go AS, Browner WS: Cardiac outcomes after regional or general anesthesia: Do we have the answer? A nesthesiology 1996; 84: 1–2
Bode RH, Lewis KP, Zarich SW, Pierce ET, Roberts M, Kowalchuk GJ, Satwicz PR, Gibbons GW, Hunter JA, Espanola CC, Nesto RW: Cardiac outcome after peripheral vascular surgery: Comparison of general and regional anesthesia. A nesthesiology 1996; 84: 3–13
O’Hara DA, Duff A, Berlin JA, Poses RM, Lawrence VA, Huber EC, Noveck H, Strom BL, Carson JL: The effect of anesthetic technique on postoperative outcomes in hip fracture repair. A nesthesiology 2000; 92: 947–57
Mangano DT, Layug EL, Wallace A, Tateo I: Effect of atenolol on mortality and cardiovascular morbidity after noncardiac surgery: Multicenter study of Perioperative Ischemia Research Group. N Engl J Med 1996; 335: 1713–20
Poldermans D, Boersma E, Bax JJ, Thomson IR, van de Ven LL, Blankensteijn JD, Baars HF, Yo TI, Trocino G, Vigna C, Roelandt JR, van Urk H: The effect of bisoprolol on perioperative mortality and myocardial infarction in high-risk patients undergoing vascular surgery: Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group. N Engl J Med 1999; 341: 1789–94
Lee TH: Reducing cardiac risk in noncardiac surgery. N Engl J Med 1999; 341: 1838–40
Posner KL, Van Norman GA, Chan V: Adverse cardiac outcomes after noncardiac surgery in patients with prior percutaneous transluminal coronary angioplasty. Anesth Analg 1999; 89: 553–60