Abnormal and normal Q waves in inferior ECG leads

Student thesis: Master thesis (including HD thesis)

  • Saba Ali Jasab Mehdi
5. Term (Master thesis), Medicine, Master (Master Programme)
Identifying pathologic Q wave is made by measurement of amplitude and duration and to be pathological both should exceed a determined extent. However, it has not been investigated how the amplitude and/or duration contribute in the prediction of prognosis when present in the inferior leads.

We sought the association between Q wave´s duration and amplitude in inferior leads and prognosis.

By taking advantage of digitalized ECGs; we could identify three exclusive populations to investigate different Q wave morphology in the inferior leads (II, III and aVF) and their prognostic value after a follow-up period of 5 years. Danish registries were used to obtain data on diagnosis and outcomes. We used multivariate-adjusted Cox proportional hazards model to estimate the risk of mortality of Q waves when present with only pathologic duration, only pathologic amplitude and both in inferior leads. Individuals with normal Q waves in the investigated lead were used as a reference.

We identified 36,645 individuals for lead II, 8,129 for lead III and 42, 892 for lead aVF. The mortality rates in the study population for lead III, II and aVF were 15.7%, 9.1% and 10.2%, respectively. Multivariate-adjusted risk for mortality was statically significant for individuals with Q waves with only pathologic duration in lead II [hazard ratio (HR): 1.48, confidence interval (95% CI): 1.08-2.02], and for lead aVF (HR: 1.17, CI: 1.05-1.29) and only pathologic amplitude (HR: 1.36, CI: 1.20-1.55 and HR: 1.52, CI: 1.35-1.71) when present in lead II and aVF respectively.
Q waves with only pathologic duration in lead III were also associated with increased mortality (HR: 2.52, CI: 1.44-4.42).

This study showed that presence of Q wave with only pathologic duration (≥ 30 msec) or only pathologic amplitude (≥ 100 mV) in one inferior lead (II or aVF) accompanied with presence of Q wave with amplitude ≥ 100 mV and duration ≥ 30 msec in another inferior lead were associated with increased mortality.
Publication date21 Dec 2015
Number of pages22
ID: 224383490