Competency in ECG Interpretation Among Medical Students

Background

Interpretation of electrocardiogram (ECG) is an essential skill in cardiology, as well as in family, internal, and emergency medicine [1]. The 12-lead ECG is commonly used for screening and diagnosis of heart diseases, including many life-threatening disorders [2,3]. The benefits of correct interpretation of ECG has been clearly demonstrated in patients with cardiac arrest or acute myocardial infarction, in which ECG signs directly determine appropriate treatment [4,5].

Several studies have highlighted deficiencies in ECG interpretation among medical students and residents from different countries [6]. In Poland, the Ministry of Science and Higher Education standards for medical faculties specify that medical graduate should be able to perform and interpret standard resting ECG. However, little is known whether current education in medical schools guarantees competency in ECG interpretation.

Despite a variety of educational resources available, there is still a common belief among Polish medical students and physicians that ECG interpretation is one of the most challenging parts of the final exams in medical schools and in the specialization exams in internal medicine or cardiology. We hypothesized that this difficulty may result from ineffective education in ECG interpretation in medical schools.

Therefore, we aimed to assess the basic skills in the interpretation of ECG among Polish medical students. We also analyzed whether the skills are developed during the process of medical education.

Material and Methods

STUDY DESIGN:

We developed an anonymous internet survey aiming to investigate the ECG interpretation skills of Polish medical students. Questionnaire design prevented multiple responses by the same person by prohibiting the use of a single Internet Protocol (IP) address more than once. Before starting the survey, participants were informed about the topic and the purpose of the study. They were also instructed how to complete the questionnaire.

STUDY POPULATION:

Undergraduates from all 12 medical schools in Poland were asked to complete the questionnaire, available online from April 4^th to May 20^th, 2015. The survey was distributed by members of the Student’s Scientific Group at the Jagiellonian University Medical College using social media, mailing lists, discussion groups, and online medical students’ media to reach the largest number of recipients. Students of all years were allowed to complete the questionnaire, but final analysis was restricted to students in clinical years (4^th–6^th), and students in preclinical years (1^st–3^rd) were used as controls to assess the effect of studying medicine on competency in ECG interpretation.

WEB-BASED SURVEY:

The survey was divided into 4 blocks:

Each question concerning the interpretation of a single ECG strip had a response time limit of 90 seconds. Each question was displayed independently, without the possibility to return to the previous one. If the time limit was exceeded, the next question was automatically displayed.

ECG SELECTION:

Nineteen ECGs were selected by the authors from the ECG textbooks, with permission of the editor [7,8]. After the ECG selection, 7 cardiology consultants were asked to independently interpret the ECG strips and complete the questionnaire. Agreement between the consultants and authors in ECG interpretation must have been 100% to include the ECG into the final questionnaire. During this consultation, 1 ECG strip was excluded and 18 were left in the questionnaire.

ANSWERS EVALUATION:

For the multiple-choice closed-ended questions, the correct answers were identified automatically. For the open-ended questions, a list of acceptable diagnoses was provided before starting the study. Only the answers that matched the pre-specified diagnoses were considered as correct.

STATISTICAL ANALYSIS:

The proportions of correct answers to individual questions were calculated by dividing the number of correct answers to a question by the total number of answers to this question. The proportion of correct answers to a single block of questions was calculated by dividing the number of correct answers to all questions from this block by the total number of questions in this block.

Categorical variables were described as counts and percentages and continuous variables as means ± standard deviations. We used the chi-square test to compare differences in ECG interpretation skills according to pre-specified criteria: gender, year of study, self-directed learning, attendance at regular ECG classes, and self-reported competency in ECG interpretation. Continuous variables were compared using Student’s t-test.

To assess which factors significantly influenced competency in ECG interpretation, we used the multivariable logistic regression model. The outcome variable was the correct answer to at least 15 questions, which is consistent with competency greater than 80%; this is a commonly-used threshold for a good grade on exams. The following independent variables were included in this model: gender, being in clinical years, ECG self-learning, membership in cardiology students’ scientific groups, and attendance at ECG classes. The significance level was set at p <0.05. Statistical analysis was performed with Statistica PL software (StatSoft, Inc. (2010) STATISTICA (data analysis software system), version 9.1. Tulsa, USA (www.statsoft.com).

Results

GROUP CHARACTERISTICS:

A total of 536 medical students (females: n=299, 55.8%; males n=237, 44.2%), aged 19 to 31 (23±1.6) years from all Polish medical schools participated in our survey. Most students (n=387; 72%) were in clinical years 4th–6th. Most of them (70%) declared to have attended regular classes on ECG interpretation, but the majority (82%) assessed the number of such classes as too small. More than half of students (55%) declared self-education of ECG. Characteristics of the study group are presented in Table 1. Only 164 (31%) participants assessed their ECG interpretation skills as good; these were more often students in their clinical rather than preclinical years (Table 1). Students’ competency in ECG interpretation according to medical school is presented in Table 2.

COMPETENCY IN ECG INTERPRETATION:

Most students of clinical years (86%) were able to correctly interpret the primary ECG parameters such as heart rate, heart rhythm, and electrical axis of the heart; 69% of them were able to recognize ECG emergencies and only 58% were able to recognize common ECG abnormalities such as ischemia, rhythm disorder, and cardiac chambers hypertrophy (Figure 1). The overall rate of correct responses was 66%. As shown in Figure 1, competency in ECG interpretation was higher in students in their clinical years than in preclinical students. There were no significant differences between 4th-, 5th-, and 6th-year students with respect to competency in interpreting primary ECG parameters (88%, 84%, and 88%, respectively), emergencies (69%, 69%, and 69%, respectively), other common ECG abnormalities (57%, 58%, and 59%, respectively), and overall competency (66%, 66%, and 67%, respectively).

DETERMINANTS OF COMPETENCY IN ECG INTERPRETATION:

Overall accuracy of ECG interpretation in students in their clinical years was similar in men and women, but male students were better trained in interpretation of primary ECG parameters (Figure 2A). Competency in ECG interpretation was higher in students who reported self-learning of ECG interpretation than in those who did not learn ECG by themselves (Figure 2B), but we did not find any relationship between attending regular ECG classes and the competency in ECG interpretation (Figure 2C). Students usually could estimate their ability to interpret ECGs correctly. Those who assessed their skills as good had overall rate of correct responses of 69%, as compared to those who assessed their skills as bad (61%, p<0.0001).

Logistic regression analysis (Table 3) showed that being in the clinical years and self-learning of ECG interpretation determined competency in ECG interpretation in medical students.

Discussion

STRENGTHS AND LIMITATIONS:

Our study has several strengths. First, the respondents were enrolled from all medical schools in Poland, thereby making the results generalizable to the entire Polish medical education system. Second, we specified the areas in ECG interpretation skills that need to be improved. Finally, we showed the impact of current ECG education in medical schools on competency in ECG interpretation.

There are also several limitations to this study that should be considered. Participation in our survey was voluntary; therefore, our sample may not be representative of all Polish medical students. We believe that students interested in ECG interpretation accounted for most of the respondents; therefore, the level of competency in ECG interpretation might be overrated in our study. Students completed they survey without supervision; therefore, they could have used additional resources to answer the questions and might have repeated the survey many times to get the best result. We think, however, that this is unlikely as the survey was anonymous, we did not reward good responses, and the time for each response was limited. Additionally, the survey could have been sent only once from a specific computer IP address.

Conclusions

Polish medical students in their clinical years have a good level of competency in interpreting the primary ECG parameters. However, their ability to recognize ECG signs of life-threatening disorders and common heart abnormalities is insufficient. Competency in ECG interpretation is determined mainly by self-education, while attendance at regular ECG classes failed to affect the ECG interpretation skills. New evidence-based educational methods should be applied when teaching medical students.