Cardiovascular diseases, principally ischemic heart disease and stroke, are the leading cause of global mortality.¹ The main cause of ischemic heart disease is coronary artery disease (CAD). The Framingham Heart Study² and its cohorts defined the risk factors (RF) for CAD, changing the way preventive medicine is currently applied. The growth of the population and the prevalence of associated CAD makes it essential to identify patients at high risk for the occurrence of cardiac events.

Coronary angiography is the gold standard exam for assessing coronary anatomy and diagnosing CAD.³ The incidence of complications related to the method is less than 1%.⁴ The risk of adverse events for each patient depends on a variety of factors including the following: demographic characteristics, cardiovascular anatomy, clinical condition, comorbidities, practitioner experience, and the type of procedure involved. The increased availability of catheterization laboratories in Brazil has made coronary angiography more accessible to patients who suffer from CAD. This procedure is available in all major cities of Brazil, and it is provided by the Brazilian Unified Health System (SUS).

There is very little data in the Brazilian medical literature regarding the results of coronary angiography. Moreover, such literature sheds a bit of light on the question of how safe this invasive procedure is when administered in a public university hospital.

This article aims to assess the clinical profile and its associations with the results of coronary angiography and to evaluate the safety of coronary angiography in a public university hospital.

In this study, the comparison of the clinical profile with the results of coronary angiography is relevant for the identification of the clinical characteristics that are associated with CAD in the population of patients treated at a public university hospital.

It is difficult to compare these results with those produced in other studies because of the differing inclusion criteria. However, this study included a comprehensive consideration of the definition of CAD; therefore, the comparison based on the presence of obstructive CAD was not impaired, despite the difference in definitions used in other studies. Limited data were found for comparison of LMCA stenosis in the literature. In Chart 1, the main clinical variables and the presence of CAD in the studied population are described together with the results of contemporary studies that also evaluated clinical characteristics, RF and CAD in patients undergoing coronary angiography.

Obstructive CAD in the studied population was detected in 65.0% of cases and 58.2% of patients had severe stenosis. These figures are below the values estimated (73% to 80%) by the ACC.⁸ The study conducted by Patel et al.⁹ provided a comprehensive examination of CAD in patients who underwent coronary angiography. In this study, over 1,989,779 exams of the National Cardiovascular Data Registry (NCDR) were conducted between January 2004 and April 2008. The researchers found a prevalence of severe CAD in 60.3% of the sample population, but only 37.6% in patients who were suspected of having stable CAD. In cases of prevalence of CAD above moderate degrees of stenoses, the percentage in stable patients rose to 41%. The present study showed a similar result in the prevalence of CAD in the sample population, but a higher prevalence among patients with suspected stable CAD (Figure 2).

Costa Filho et al.¹⁰ published a study examining 830 patients with suspected stable CAD referred for elective coronary angiography. In their sample, 27.8% of patients had CAD with severe stenosis; when considering CAD above moderate degree of stenosis, the prevalence rose to 32.2%. That study included only stable patients and also excluded patients who were previously diagnosed with CAD; those differences in method design might explain our study's higher prevalence of obstructive CAD.

The multivariate analysis indicated that male sex and older age were independent risk predictors for CAD and LMCA stenosis. Additionally, it is evident there is an increase in proportional risk with age for all the analyzed outcomes, as well as the result found by Patel et al.⁹ that demonstrated an increment in odds ratio of 1.29 in each succeeding age cohort of 5 years older (95% confidence interval: 1.28 to 1.30).

As expected, all classical RF showed a statistically significant association with CAD. The number of RF has been highly correlated with CAD outcomes, as shown in Table 4. A study published in Jordan has shown that the patients who underwent coronary angiography had at least 1 RF.¹¹

Many studies do not consider peripheral arterial disease as a RF for CAD,^12,13 but recent studies have “contradicted” that notion.^14–19 The REACH Registry has conducted a multicenter study for 3 years involving 67,888 patients.^20,21 There was an incidence of 14.8% of acute myocardial infarction, brain stroke, and death in patients diagnosed with peripheral arterial disease, greater than the one found in the group of patients who had suffered from only CAD (11.6%). In this study, only 48 (2.6%) patients had this comorbidity, a prevalence similar to that of the population of another Brazilian study.¹⁰ This variable proved to be an independent risk predictor for obstructive CAD, as shown in the multivariate analysis. These data highlight the importance of this condition, which often goes unnoticed in the clinical examination.

Only 19.7% of patients underwent any non-invasive test for ischemia before coronary angiography, and the most frequent method was the cardiac stress test (61%). This rate is below those obtained in other populations (64.8% and 88.9%) examined in similar studies.^10,22 Other studies have shown that non-invasive tests for ischemia were a risk predictor for CAD.^9,10

Only a small number of patients who underwent coronary angiography suffered from serious complications. This is a notable result in light of the fact that this study was conducted at a public university hospital, focused on resident training. The findings of this study are consistent with those discovered in other studies.⁴ Even though the number of complications is very low, the statistics of mortality presented a significant difference when compared to another recent study with 43,786 coronary angiography procedures and only 0.011% mortality.²³ The highest rate of this complication in the current sample might be related to the fact that this service is a training center; however, we would need more concrete studies to evaluate this. Deaths were caused by acute LMCA occlusion in 1 case and in 2 patients presenting cardiogenic shock referred for emergency coronary angiography.

The low incidence of complications can be related to the high number of stable patients (77.2%), as well as the fact that most procedures were performed via radial access (91.7%). As previously demonstrated by Jolly et al.²⁴ only 1.2 % of vascular complications in the group were due to radial access, compared to 3.0% in the femoral access group (p < 0.001). Romagnoli et al.²⁵ demonstrated a lower mortality index in the group of patients with ST-elevation myocardial infarction (STEMI) who underwent the procedure via radial versus femoral access (5.2% versus 9.2%; p = 0.02). The reduced number of procedures via femoral artery access made vascular surgery unnecessary in all the cases. Furthermore, surgical intervention for vascular complications is very rare when the procedure is performed through the radial artery;²⁶ on the other hand, when the procedure is performed via femoral access, the occurrence of complications, such as arteriovenous fistula, pseudoaneurysm, and retroperitoneal hematoma increase the frequency of surgical approach to up to 1.6%.²⁷ Regarding the rate of neurological events, this complication did not occur in the present series, differing from another recent study that presented a rate of neurological events of 0.056%.²³

This study has limitations. As this is an observational cross-sectional study, the determination of causality is not achievable; in addition, variables with low prevalence require very large samples for better statistical analysis. Also, because it is a single-center study, carried out in a tertiary hospital dedicated to teaching in the state of Rio de Janeiro, questions may arise regarding the external validity of the results.

Access to medical records and characteristics of patients referred via the SER were limited several times. In these cases, clinical data were characterized through a brief anamnesis before the procedure.

Despite the limitations, the availability of an organized database led to a satisfactory numerical result. Furthermore, these findings will contribute to the improvement of HUPE's interventional cardiology service. In light of the discoveries of the present study, it is possible to improve the specialization for training interventionists and the quality of patient care. Moreover, these findings can encourage other medical practitioners to expand their data on this subject. By virtue of the quantitative contributions of this study, other medical practitioners will be able to refine their numerical figures and generate multicenter analyses with greater statistical robustness.

Classic RF showed an association with CAD. Advanced age, male sex, high number of RF, patient referral by HUPE, and peripheral arterial disease were considered predictors of risk for CAD. The low incidence of complications suggests that coronary angiography is a safe procedure to be conducted in a public university hospital.