Browsing by Subject "ECG"

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    Clinically contextualised ECG interpretation: the impact of prior clinical exposure and case vignettes on ECG diagnostic accuracy
    (2021-08-03) Viljoen, Charle A.; Millar, Rob S.; Manning, Kathryn; Hoevelmann, Julian; Burch, Vanessa C.
    Background ECGs are often taught without clinical context. However, in the clinical setting, ECGs are rarely interpreted without knowing the clinical presentation. We aimed to determine whether ECG diagnostic accuracy was influenced by knowledge of the clinical context and/or prior clinical exposure to the ECG diagnosis. Methods Fourth- (junior) and sixth-year (senior) medical students, as well as medical residents were invited to complete two multiple-choice question (MCQ) tests and a survey. Test 1 comprised 25 ECGs without case vignettes. Test 2, completed immediately thereafter, comprised the same 25 ECGs and MCQs, but with case vignettes for each ECG. Subsequently, participants indicated in the survey when last, during prior clinical clerkships, they have seen each of the 25 conditions tested. Eligible participants completed both tests and survey. We estimated that a minimum sample size of 165 participants would provide 80% power to detect a mean difference of 7% in test scores, considering a type 1 error of 5%. Results This study comprised 176 participants (67 [38.1%] junior students, 55 [31.3%] senior students, 54 [30.7%] residents). Prior ECG exposure depended on their level of training, i.e., junior students were exposed to 52% of the conditions tested, senior students 63.4% and residents 96.9%. Overall, there was a marginal improvement in ECG diagnostic accuracy when the clinical context was known (Cohen’s d = 0.35, p < 0.001). Gains in diagnostic accuracy were more pronounced amongst residents (Cohen’s d = 0.59, p < 0.001), than senior (Cohen’s d = 0.38, p < 0.001) or junior students (Cohen’s d = 0.29, p < 0.001). All participants were more likely to make a correct ECG diagnosis if they reported having seen the condition during prior clinical training, whether they were provided with a case vignette (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.24–1.71) or not (OR 1.58, 95% CI 1.35–1.84). Conclusion ECG interpretation using clinical vignettes devoid of real patient experiences does not appear to have as great an impact on ECG diagnostic accuracy as prior clinical exposure. However, exposure to ECGs during clinical training is largely opportunistic and haphazard. ECG training should therefore not rely on experiential learning alone, but instead be supplemented by other formal methods of instruction.
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    Open Access
    Electrocardiographic predictors of poor outcome in acute myocardial infarction
    (2024) Shirley, Samantha Shirley; Chin, Ashley; Viljoen, Charle; Hitzeroth, Jens; Hoevelman, Julian
    Introduction: Myocardial infarction (MI) is a major cause of death worldwide. An ECG is indicated in all patients with suspected MI. The aim of this study was to evaluate electrocardiographic predictors of outcome in acute coronary syndrome (ACS). Methods: We analyzed 12-lead ECGs of 301 consecutive patients admitted to the coronary care unit (CCU) at a tertiary centre during 2016 with a diagnosis of ACS. ECGs were done on admission, and after that daily throughout the hospitalisation. Poor outcome was defined as all-cause mortality within a three-year period after the index MI. Results: This cohort of 301 patients (42.2% female) with a mean age of 57.4±11.9 years, presented with either ST-elevation myocardial infarction (STEMI, 57.5%) or non-ST elevation myocardial infarction (NSTEMI, 42.5%). Fifty-one (16.9%) patients died within three years after their index presentation. Multivariable regression analyses revealed that left atrial enlargement (LAE, odds ratio [OR] 3.91 [95% confidence interval [CI] 1.39-11.02], p=0.010) and ST depression (OR 3.64 [95% CI 1.33-9.93], p=0.012) were predictive of poor outcome, wheras sinus rhythm with normal rate was associated with a better prognosis (OR 0.33 [95% CI 0.12- 0.91] p=0.032). Patients with two or more risk factors (i.e., LAE, ST depression, sinus tachycardia) experienced higher mortality rates (p<0.001).Conclusion: Our study showed that the ECG has prognostic value in patients presenting with acute MI. ECG features that were independently associated with increased mortality within the first three years of MI (LAE, ST depression and/or sinus tachycardia) could assist with risk stratification of patients presenting with ACS.