Impact of complex lesions on radiological exposure during percutaneous coronary intervention

Azevedo, Eduardo Mascarenhas; Gomes, Henrique Basso; Yordi, Luis Maria; Moura, Mauro Régis da Silva; Laguna, Amanda; Fischer, Leandro dos Santos; Cardoso, Cristiano de Oliveira

doi:10.1590/S2179-83972013000100011

Abstracts

BACKGROUND: Percutaneous coronary interventions (PCIs) in complex lesions are increasingly common in daily practice. The objective of this study was to determine the impact of complex lesions on radiological exposure during PCI. METHODS: Prospective cohort study including patients undergoing PCI between August 2010 and December 2011. Clinical, angiographic and radiation exposure characteristics were recorded in a dedicated database. Patterns of radiation exposure (total dose received, fluoroscopy time and dose-area product) were determined in patients undergoing PCI for non-complex (A/B1) and complex (B2/C) lesions. Data were analyzed by the SPSS 18.0 program. Independent radiation exposure predictors were determined by multiple logistic regression. RESULTS: We analyzed 413 PCIs, 83 lesions in group A/B1 and 330 in group B2/C. There were no clinically significant differences between groups. The median radiation dose received by patients was significantly higher in group B2/C (1,103.9 mGy vs 866.6 mGy; P < 0.01). The dose-area product (43,484 mGy.cm² vs 58,327 mGy.cm²; P < 0.001) and fluoroscopy time (9 ± 6 minutes vs 12.1 ± 9.5 minutes; P = 0.001) were also significantly higher in group B2/C. Predictors of increased radiation exposure were weight [odds ratio (OR) 1.02 for each increase of 1 kg, confidence interval (CI) 1.01-1.036; P = 0.004], type B2/C lesion (OR 1.9, CI 1.002-4.96; P = 0.002). CONCLUSIONS: Patients undergoing PCI in complex lesions are significantly more exposed to radiation. Weight and lesion type (B2/C) are predictors of increased radiation exposure.

Angioplasty; Radiation, ionizing; Radiation exposure

INTRODUÇÃO: Intervenções coronárias percutâneas (ICPs) em lesões complexas são cada vez mais comuns na prática diária. O objetivo deste estudo foi determinar o impacto das lesões complexas na exposição radiológica durante ICP. MÉTODOS: Estudo de coorte prospectiva incluindo pacientes submetidos a ICP entre agosto de 2010 e dezembro de 2011. Características clínicas, angiográficas e de exposição à radiação foram registradas em banco de dados específico. Os padrões de exposição à radiação (dose total recebida, tempo de fluoroscopia e produto dose-área) foram determinados em pacientes submetidos a ICP de lesões não-complexas (A/B1) e complexas (B2/C). Os dados foram analisados em programa SPSS 18.0. Preditores independentes de exposição à radiação foram determinados por regressão logística múltipla. RESULTADOS: Foram analisadas 413 ICPs, sendo 83 lesões no grupo A/B1 e 330 no grupo B2/C. Não ocorreram diferenças clínicas significativas entre os grupos. A mediana de radiação recebida pelos pacientes foi significativamente maior no grupo B2/C (1.103,9 mGy vs. 866,6 mGy; P < 0,01). O produto dose-área (43.484 mGy.cm² vs. 58.327 mGy.cm²; P < 0,001) e o tempo de fluoroscopia (9 ± 6 minutos vs. 12,1 ± 9,5 minutos; P = 0,001) também foram significativamente maiores no grupo B2/C. Os preditores de exposição radiológica aumentada foram peso [razão de chance (RC) 1,02 para cada aumento de 1 kg, intervalo de confiança (IC) 1,01-1,036; P = 0,004] e lesão tipo B2/C (RC 1,9, IC 1,002-4,96; P = 0,002). CONCLUSÕES: Pacientes submetidos a ICP em lesões complexas são significativamente mais expostos à radiação. Peso e tipo de lesão (B2/C) são preditores de exposição radiológica aumentada.

Angioplastia; Radiação ionizante; Exposição a radiação

ORIGINAL ARTICLE

^ICardiologist and hemodynamicist physician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^IICardiologist and hemodynamicist physician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^IIICardiologist and hemodynamicist physician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^IVCardiologist and hemodynamicist physician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^VRadiology and imaging diagnosis technician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^VIRadiology and imaging diagnosis technician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

^VIIMaster. Cardiologist and hemodynamicist physician at Instituto de Cardiologia do Rio Grande do Sul/Fundação Universitária de Cardiologia. Porto Alegre, RS, Brazil

Correspondence to

ABSTRACT

BACKGROUND: Percutaneous coronary interventions (PCIs) in complex lesions are increasingly common in daily practice. The objective of this study was to determine the impact of complex lesions on radiological exposure during PCI.

METHODS: Prospective cohort study including patients undergoing PCI between August 2010 and December 2011. Clinical, angiographic and radiation exposure characteristics were recorded in a dedicated database. Patterns of radiation exposure (total dose received, fluoroscopy time and dose-area product) were determined in patients undergoing PCI for noncomplex (A/B1) and complex (B2/C) lesions. Data were analyzed by the SPSS 18.0 program. Independent radiation exposure predictors were determined by multiple logistic regression.

RESULTS: We analyzed 413 PCIs, 83 lesions in group A/B1 and 330 in group B2/C. There were no clinically significant differences between groups. The median radiation dose received by patients was significantly higher in group B2/C (1,103.9 mGy vs 866.6 mGy; P < 0.01). The dose-area product (43,484 mGy.cm² vs 58,327 mGy.cm²; P < 0.001) and fluoroscopy time (9 ± 6 minutes vs 12.1 ± 9.5 minutes; P = 0.001) were also significantly higher in group B2/C. Predictors of increased radiation exposure were weight [odds ratio (OR) 1.02 for each increase of 1 kg, confidence interval (CI) 1.01-1.036; P = 0.004], type B2/C lesion (OR 1.9, CI 1.002-4.96; P = 0.002).

CONCLUSIONS: Patients undergoing PCI in complex lesions are significantly more exposed to radiation. Weight and lesion type (B2/C) are predictors of increased radiation exposure.

Descriptors: Angioplasty. Radiation, ionizing. Radiation exposure.

Fluoroscopy-guided interventional procedures are performed in large numbers around the world, with increasing frequency over the past 20 years.¹ In addition to the progressive increase in the number of interventions, procedure complexity has also increased.^2,3

Interventions in complex lesions⁴ involve greater technical difficulty, which results in higher costs, contrast volume, procedure time, and radiation exposure.^5-7 Recent studies have demonstrated that many percutaneous coronary interventions (PCIs) exceed the dose of 2 Gy, the threshold for development of skin lesions. However, the literature has no specific studies focusing on lesion complexity.

Therefore, the objective of this study was to determine the impact of complex lesions on radiological exposure during PCI.

METHODS

Design

This was a prospective cohort study including patients undergoing PCI between August 2010 and December 2011.

Sample

After signing the informed consent form approved by the local ethics and research committee, patients requiring PCI had their procedures monitored in order to record the patterns of radiological exposure. Technical details of the PCIs were prospectively recorded and entered into a specific database.

Analysed characteristics

Data on age, gender, risk factors for cardiovascular disease, clinical presentation and procedure indications, ventricular function, number of affected vessels, treated vessels, characteristics of lesions, and success rate were collected and analyzed. Specific data on radiological exposure (dose received, dose-area product, and fluoro- scopy time) were also collected.

Radiological exposure parameters

The radiological exposure of patients was meas- ured by the amount of incoming radiation on the skin (cumulative air KERMA [Kinetic Energy Released per unit MAss]). The fluoroscopy time and dose-area product were also measured to determine the time of radiological exposure and the irradiated area, respectively.

The procedures were performed in equipment with Philips Allura Xper FD10 monoplane detectors (Philips = Einthoven, Netherlands) with three magnification fields (15 cm, 20 cm, and 25 cm), double filter (copper and aluminium), and standard programming with image acquisition rate of 15 frames/second.

Statistical Analysis

The patients were divided into two groups for comparison, according to the classification of the type of lesion proposed by the American College of Cardiology/American Heart Association (ACC/AHA):⁸ patients undergoing PCI of noncomplex (type A/B1) and complex lesions (type B2/C). Data were prospectively collected and stored in a database using ACCESS software. For analysis, SPSS for Windows version 18.0 was used. The chi-squared test, Student's t-test, and the Mann-Whitney test were used for comparison. Independent predictors of increased radiation exposure (dose > 2 Gy) were determined by multiple logistic regression. Two-tailed p-value < 0.05 was considered statistically significant.

RESULTS

During the study period, 413 PCIs were analyzed: 83 in the group of A/B1 lesions and 330 in the group of B2/C lesions.

Patients in both groups had similar clinical profiles, except for the higher prevalence of dyslipidaemia in the group A/B1. Regarding medications, the clinical treatment was similar between groups (Table 1).

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It can be observed that the patients in group B2/C had higher angiographic complexity (Table 2). The percentage of stenosis pre- (76.9 ± 12.9% vs. 78.5 ± 13.7%; P = 0.34) and post-procedure (3.8 ± 5.6% vs. 1.6 ± 12.8%; P = 0.14) was similar between groups. Pre-procedure Thrombosis in Myocardial Infarction (TIMI) 2/3 coronary flow was more frequent in the A/B1 group (95% vs. 86.5%; P = 0.002), but it became similar in both groups after the PCI (100% vs. 99.1%; P = 0.30).

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The median radiation dose received by patients was significantly higher in group B2/C (Table 3). The fluoroscopy times (9 ± 6 minutes vs. 12.1 ± 9.5 minutes; P = 0.001), the number of radiographies (17.8 ± 7.1 vs. 21.2 ± 9.3; P = 0.002), and the total number of frames (986 ± 423 vs. 1,166 ± 540; P = 0.005) were also higher in the B2/C group.

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In four (4.8%) PCIs in A/B1 the group and in 48 (14.5%) in the B2/C group (P < 0.01) the 2 Gy dose was exceeded.

The following predictors of increased radiation exposure were determined by multiple logistic regression: weight (odds ratio [OR], 1.02 per 1 kg increase; confidence interval [CI] of 1.01 to 1.036; P = 0.004), and lesion type B2/C (OR 1.9; CI 1.002 to 4.96; P = 0.002).

DISCUSSION

The present study determined that the radiological exposure is higher in patients submitted to PCI in complex lesions. The harmful effects of radiation, mainly dose-dependent (deterministic), have been widely reported in procedures involving ionising radiation.^9-12 However, physicians' knowledge about the harmful effects of radiation is not proportional to their exposure.¹³

Along with the growing number of more complex procedures, hemodynamics equipment has also developed. The more modern flat panel technology is very attractive because it allows for higher quality and better image resolution.¹⁴ However, clinical studies have demonstrated that the incorporation of this technology causes higher radiation exposure.^15,16 For this reason, scientific societies have published recommendations and guidelines aiming to reduce radiation levels during procedures.^1,17

Since the publication of the SYNergy between Percutaneous Coronary Intervention and Cardiac Surgery Study (SYNTAX),¹⁸ which demonstrated that patients with low angiographic and anatomical complexity (score < 22) have a favourable clinical outcome when submitted to PCI with drug-eluting stents, interventions in multiple vessels have become common in hemodynamics laboratories. However, little has been discussed about radiological exposure. Although this study does not refer to the type of intervention (single or multivessel), the simple fact that PCI was performed in complex lesions promoted a 27% increase in radiation exposure for the patient. This fact is relevant, as increasingly more cases of radiation-related lesions have been reported in patients and health professionals.¹² In practice, health professionals can minimize occupational radiation by using individual lead protection clothing associated with physical shields. However, patients do not have this protection.

According to the International Atomic Energy Agency (IAEA), the radiation exposure during cardiac diagnostic and therapeutic procedures should not exceed 2 Gy. However, that dose was exceeded in 14% of patients undergoing complex interventions in the present study. This fact is relevant, as most PCIs were performed in type B2/C lesions, as in the real world.⁴ Considering that many patients were obese,¹⁹ a known predictor of increased exposure, overexposure can be even greater. It is therefore essential that professionals take that into consideration and minimize radiation exposure during radiological assessment.

Study limitations

The main limitation of the present study is the small number of patients included. Moreover, the dose received by the interventional physician could not be measured.

CONCLUSIONS

Patients submitted to PCI in complex lesions are significantly more exposed to radiation. Weight and complex lesions (B2/C type) are predictors of increased radiation exposure.

CONFLICT OF INTEREST

The authors declare no conflicts of interests.

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¹⁸
The SYNergy between Percutaneous Coronary Intervention and Cardiac Surgery (SYNTAX) Study. In: Annals of the European Society of Cardiology Congress; 2008; Munich, Germany.
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