Introduction:
Tetralogy of Fallot (TOF) and Ventricular Septal Defect (VSD) patients have non-diagnostic Q-waves within inferior (II, III, aVF) or septal (V1-V2) leads on ECG, perhaps due to incomplete conduction through septal defects. Non-diagnostic Q-waves tend to either be wide within a single lead, or deep (3-4mm) in contiguous leads, but do not meet diagnostic criteria for infarct.
Hypothesis:
Non-Adult Congenital Heart Disease (ACHD) physicians may inaccurately characterize non-diagnostic Q-waves as pathologic opposed to expert interpretation by ACHD-trained physicians in VSD and TOF patients. Thus, misinterpreting ECGs to suggest prior infarct and decreasing their positive predictive value (PPV).
Methods:
With application of pre-specified inclusion and exclusion criteria, we retrospectively reviewed 72 ECGs from TOF or VSD patients at Penn State Hershey Medical Center from 2002-2020 that were separately read by ACHD and non-ACHD specialists. Primary outcomes were ECGs with diagnosed Q-waves in two separate distributions, inferior or septal leads, by both groups using standard criteria for Q-wave infarct. Reported measures were sensitivity, specificity, PPV, and negative predictive value (NPV).
Results:
The 72 subjects with isolated TOF or VSD had a mean age of 39 years and 63% were male. Total disease prevalence (presence of Q-waves) was 4.6%. Q-wave infarct diagnosed by non-ACHD physicians had a sensitivity and specificity of 33% and 74% respectively. Their PPV was 5.87% and NPV was 95.85%.
Conclusions:
This retrospective cohort analysis of TOF and VSD patient ECGs showed the low PPV of non-ACHD physician diagnosis of Q-waves in this respective population. Misinterpretation and misdiagnosis of infarct based off ECG, has ramifications for both the patient and medical system as a whole. Sequelae include, but are not limited to, increasing patient risk for unwarranted medical treatment and affecting hospital billing and insurance coverage.
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