Duchenne muscular dystrophy (DMD) patients universally develop cardiomyopathy (DMD-C) with myocardial fibrosis by late gadolinium enhancement (LGE), a decline in left ventricular ejection fraction (LVEF) follows, leading to premature death. Cardiac magnetic resonance imaging (CMR) has been instrumental for early detection to initiate and titrate cardiac therapy, improving survival in the US, but is expensive. Around 200K DMD patients live in developing countries where resources are limited. Thus, cardiac dysfunction goes undetected and untreated, causing a shorter lifespan. Electrocardiograms (ECG) are cost-effective screening tests used in various diseases with a unique pattern in DMD (Figure 1). In these countries, ECG may provide a valuable tool to better risk-stratify patients and help allocate limited resources to those with higher risk.
Identify the positive predictive value and negative predictive value of using ECG as a cardiomyopathy screening tool based on correlation with CMR findings in DMD patients.
Retrospective analysis of 164 DMD patients who underwent ECG followed by CMR within 3 days. ECGs were screened for abnormalities that are highly correlated with DMD, including: short PR interval (< 120 msec), R/S wave ratio > 1 in lead V1, abnormal Q wave and sinus tachycardia (HR > 100/min). The association between ECG abnormalities and LGE was analyzed by Chi-Square analysis and odds ratios.
Patients with one or more ECG abnormalities were 157 (96%), 2 or more in 124 (76%) and 3 or more in 68 (41%). Prevalence of ECG abnormalities: 84 patients had a short PR interval, 86 had R/S wave ratio > 1 in lead V1, 111 patients had an abnormal Q wave, and 80 patients had sinus tachycardia. Myocardial damage by LGE was found in 15 (9%), and 4 (2%) had reduced LVEF (< 50%). Data analysis summarized in (Table 1) below shows that ECG abnormalities are associated with increased odds ratios and positive predictive value of having significant LGE findings. All of which have a P-value < 0.05 and CI of 95%. Conversely, the absence of 2 ECG abnormalities (short PR and R/S > 1 in V1) showed a high negative predictive value for LGE findings (119/127 patients, 94%).
DMD patients with specific ECG abnormalities are more likely to have myocardial damage by LGE, and patients without them are less likely to have evident myocardial damage. Thus, ECG use in countries where CMR is not available can be valuable, allowing for life-saving interventions.