Perioperative acute myocardial infarction (PAMI) is a serious complication which is the one of the leading cause of death within the first 30 days after non-cardiac surgery [1]. One million patients die from PAMI yearly [2]. Nagele et al. [3] found that preoperative hscTnT can be a specific, sensitive and rapid biomarker for categorizing the risk for PAMI and mortality in preoperative patients [4,5]. Recent studies denoted that even a sligth increase in cardiac troponins (c-T) and also hs-TcT assays which were introduced to detect the low level of c-Tns were associated with increased cardiac complications [6-8]. There is a debate about which anesthetic method is safer for myocardial tissue.

Study populations

Following getting our trial permission from our hospital local ethics and trial committee and collection of informed consent, 86 ASA I-III patients 18-65 years of age who were scheduled to undergoing elective orthopedic lower limb surgery and randomized in two groups: Group G (n=43) and Group R (n=43) undergoing surgery with spinal or general anesthesia. The trial number was 629/2013 and designed as prospective, randomized, double-blind study and conducted between January and February 2014 in at our hospital orthopedics clinics.

The study was performed by the person unaware of clinical outcomes. Anesthesia doctors and technicians were collected the blood samples but didn’t know the analysis groups. The technicians, physicians and analysts who performed the tests were not informed about the study. A Consort flow chart diagram of the trial was shown in Figure 1.

Figure 1: Consort Flow Diagram of our randomized trial.

Patient characteristics were listed in Table 1. A Mallampati score>2, long QT syndrome (acquired or congenital), cardiovascular disease, chronic obstructive lung disease, diabetes mellitus, chronic alcohol and drug using patients were excluded from the study. Hemodynamic monitoring data’s that are consist of peripheral oxygen saturation (SpO2), heart rate (HR)and mean arterial pressure (MAP) were evaluated preoperative section and patients didn’t get any premedication. Propanol and fentanyl were used to get the anesthesia induction and endotracheal intubation was performed after neuromuscular block with 0.1 mg kg-1 rocuronium in Group G. Maintenance of anesthesia was ensured with 50% N₂O/O₂ and 2-2.5% sevoflurane inhalation. When the patients were in the sitting position 15 mg 0.5% hyperbaric bupivacaine were given to the L4-L5 space in the midline to get the spinal anesthesia in Group R. The pinprick test and the Bromage scale were used for sensory and motor block. Surgery was started when the T10 level sensory block was reached.

Table 1: Characteristics of the study population.

Biomarker assays

Blood samples and 12-lead ECCs were taken on preoperative (baseline) and the mornings of postoperative days 1,2 and 3, collected in serum separation tubes and centrifuged. Samples were separated into aliquots and were frozen -80°C until they were assayed. Biomarker measurements were carried out in batches and no more than 2 freezethaw cycles. Hs-cTnT concentrations (presented as nanograms per liter equal to picograms per mililiter) were measured by on Cobas e601 autoanalyzer (Roche Diagnostics, Germany). Measurable Ranges were 3-10000 ng/L or pg/mL. (Limit of detection 5 ng/L) The hs-cTnT level with 10% coefficient of variation was 13 ng/L.

Statistical analysis

SPSS software (Version 18.0, SPSS Inc. Chicago, IL, USA) was used for statistical analysis. Variables were analyzed using the Kolmogorov- Simirnov test. Categorical variables were presented as percentages and parametric variables were presented as mean ± standard deviation. Non-parametric variables were expressed as median (minimummaximum). The normally distributed numeric variables were analyzed with the Student’s t-test, and non-normally distributed variables were eveluated by the Mann–Whitney U test variance analysis. The categorical variables compared with Chi-square test. P value<0.05 was accepted as statistically significant.

Before and after surgery, all patients had a level of >5 ng/L hs-cTnT concentration. Before operation Group G had a mean of 12.79 ± 22.241 ng/L and Group R had 8.44 ± 5.019 ng/L hs-cTnT. (p value: 0.079). On postoperative day 1, Group G patients had a mean hs-cTnT 11, 25 ± 19, 941 ng/L and Group R patients had a hs-cTnT9, 89 ± 10, 199 ng/L. (pvalue: 0.454) On postoperative second and third days Group G had a mean 12.56 ± 21.591 ng/L and 13.83 ± 26.992 ng/L, and Group R had mean 8.02 ± 4.042 ng/L and 17.27 ± 22.707 ng/L, (p value: 0.407 and 0.055) respectively. The distribution of these values is shown in Table 2.

Table 2: Hs-cTnT levels of preopertive day and postoperative days 1-3 (median±SD n/L)

Before and after surgery of two different anesthesia patients had a detectable hs-cTnT concentrations but not significant rise in hs-cTnT levels. In spinal anesthesia group there is slight increase near significant hs-cTnT on postoperative third day (p value: 0.055) (Figure 2)

Figure 2: The chart is showing the group G and R hs- cTnT levels. In group R a near significant increase occured on postoperative day 3 (p: 0.055).

The recent guidelines propose the use of volatile anesthetics as beneficial in high risk patients undergoing non-cardiac surgery (class IIa recommendation). A systematic review failed to retrieve studies and a small trial published in the meantime did not detect any protective effect of volatile anesthetic’s on cardiovascular end points in non-cardiac surgical patients [9-15]. In addition the numbers of studies evaluating effects of spinal anesthesia are scarce. One of these studies [16] compared selective spinal anesthesia with general anesthesia technics and did not find any significant difference regarding arrythmia and hemodynamy. Another study [17] assessed effects of anesthesia technics on myocardial ischemia and reported that anesthesia technics did not affect serum CK-MB and Troponin I levels and ST segment levels on holter ECG monitorization in elderly patients undergoing urological operations. The above mentioned studies have reported similar findings. Major cardiovascular complications and deaths did not differ in larger trials, which randomized patients to combined anesthesia techniques. The results of this trial [18] may therefore be viewed in the broader evidence context, suggesting that the applied anesthetic technique may not make a difference in the occurrence of major cardiovascular complication and death after non-cardiac surgery. Absence of preoperative ischemia is a significant risk in both general and local anesthesia. In addition silent perioperative ischemic events [19] occur frequently at postoperative period. Ischemic events may occur due to postoperative pain, decreased capacity of O₂ carrying, and acute reduction of cardiac output or blood pressure, intraoperative and postoperative bleeding, increased metabolic response to increased body temperature and shivering. Many myocardial ischemic events may not result in hemodynamic compromise. In addition ECG [16] may be normal in 25-50% of patients with coronary artery disease. Usually repeated ECGs [19] show myocardial infarction findings in case of new perioperative myocardial infarction. Therefore analysis of serum cardiac markers may be useful in suspicious myocardial ischemic events. In this study no patient displayed hemodynamic compromise and an increased level of hs-cTnT denoting myocardial ischemia. Some authors suggest the increased hs-cTnT levels may be correlated with skeletal disease but if it is skeletal disease the increase must have been persistent [20]. In our study the increase was observed on the third day not before that and this make us to consider silent complications.

Our study was done on limited population at low-risk, long-term follow-up results were absent, etc. Although, our findings are compatible with the others considering that cardiac complications are caused by supply and demand mismatch, we must follow the postoperative course for 1 month after surgery.

In conclusion, this study we found that spinal anesthesia makes near significant increase in hs-TnT level on postoperative days. However this increase in hs-cTnT were not associated with an increased incidence of cardiac complications but this finding makes us to think spinal anesthesia can be more harmful to the cardiac tissue but we need further confirmation with other larger and longer studies.

Mansuroglu C designed the research and analyzed the data. Turhan T, Yıldız N, Calcı E, Cıgırgan C and Ornek E performed the research. Karaca O and Ornek D contributed analytical tools. Mansuroglu C, Turhan T and Ornek D wrote the paper.

The authors have no financial disclosures to declare, no conflicts of interest to report, and have no commercial or proprietary interest. No commercial or proprietary interest. There was no funding.