IJCS | Volume 31, Nº5, September / October 2018

515 Table 1 - Basal clinical characteristics, according to the time of admission at the Hemodynamics service Characteristic Nighttime group Daytime group p value Male gender, n (%) 123 (77.3) 207 (72.1) 0.09 Age, years ± SD 58.9 ± 11.8 60.2 ± 12.4 0.08 Arterial hypertension, n (%) 153 (96.2) 240 (83.6) 0.06 Diabetes mellitus, n (%) 40 (25.1) 74 (25.8) 0.68 Dyslipidemia, n (%) 60 (37.7) 90 (31.3) 0.24 Smoking, n (%) 61 (38.3) 95 (33.1) 0.12 Chronic renal failure, n (%) 13 (8.1) 31 (10.8) 0.33 Previous PCI, n (%) 10 (6.2) 20 (6.9) 0.4 Previous CABG, n (%) 4 (2.5) 6 (2.1) 0.89 Statistical tests used: Pearson's chi-square test, Fisher's exact test and unpaired Student's t-test. SD: standard deviation; PCI: percutaneous coronary intervention; CABG: coronary artery bypass grafting. Table 2 - Severity of the acute myocardial infarction clinical presentation through the Killip-Kimball classification Killip-Kimball class Nighttime group n (%) Daytime group n (%) p value I 121 (76.1) 239 (83.2) 0.06 II 12 (7.5) 21 (7.3) III 6 (3.8) 3 (1.0) IV 18 (11.3) 24 (8.3) Statistical tests used: one-way Analysis of Variance (ANOVA). Barbosa et al. Primary PCI at night time Int J Cardiovasc Sci. 2018;31(5)513-519 Original Article routinely recorded in the service by the emergency room and interventional laboratory medical staff, as well as the door-to-balloon time (delay fromadmission at the referral service emergency unit until the implementation of PPCI). Statistical analysis The data obtained were stored in a Microsoft Office Excel spreadsheet for subsequent descriptive and comparative analysis according to the time of the treatment at the Hemodynamics Service. In the descriptive analysis of the data, the categorical variables were expressed as absolute and percentage frequencies, and the continuous variables as mean and standard deviation. The datawere considered as having a normal distribution through the Shapiro-Wilk’s test. For comparisons, the statistical analysis was performed using the Statistical Package for Social Sciences (SPSS), version 20.0, for Windows, and comprised Pearson’s chi-square test, Fisher’s exact test, the unpaired Student’s t-test, and one-way ANOVA, with p values <0.05 being considered statistically significant. Results During the assessed period, 522 patients were identified and referred for cardiac catheterization as a matter of urgency, of which 446 (85.4%) were diagnosed with STEMI and submitted to PPCI during the first 12 hours since symptom onset, comprising the assessed sample. Of these, the procedure was performed in the nighttime period in 159 (35.6%), and 287 (64.4%) in the daytime period. When comparing the Nighttime and Daytime Groups, no differences were observed regarding the basal clinical characteristics (Table 1). When analyzing the severity of the STEMI clinical presentation through the Killip- Kimball classification, we observed a predominance of class I in both groups, with no statistically significant difference for the classification when comparing the Nighttime and Daytime Groups, as shown in Table 2. The means of the door-to-balloon and pain-to-balloon times did not differ statistically between the Nighttime and Daytime Groups. Table 3 shows the time delays until the performance of PPCI. There was no difference regarding the mean number of stents per patient, number of drug-eluting stents, mean stent diameter and length in the two groups. The administration of acetylsalicylic acid and clopidogrel or ticagrelor was similar between the Nighttime and Daytime Groups. During the PPCI procedures, there was a higher rate of use of glycoprotein IIb / IIIa inhibitors at nighttime, with similar procedure success rates in both periods. The characteristics related to the PPCI procedures are described in table 4. The PPCI procedure success rate did not show a significant difference when the time schedules were compared (91.1% in the Nighttime Group vs. 93.3% in the Daytime Group, p = 0.38). The mean time of