P wave analysis with wavelets identifies hypertensive patients at risk of recurrence of atrial fibrillation: A case-control study and 1 year follow-up

- Wavelet analysis of ECG signals is a non-invasive, inexpensive and easy to apply method, which was reported predictive of AF recurrences in patients without structural heart disease and in those with hypertrophic cardiomyopathy; P wave wavelet analysis was never studied before in hypertensive patients with recent onset paroxysmal AF.
- Wavelet analysis identified with sufficient accuracy AF patients after successful pharmacological cardioversion from an otherwise identical cohort of hypertensive patients with no history of AF at baseline.
- Hypertensive patients with more pronounced derangements in atrial impulse formation and propagation - reflected by P waves that are longer in duration and carrying a higher mean energy as shown by wavelet analysis - experienced a significantly decreased AF-free survival during follow-up.
- Unmasking wavelet components hidden within the high voltage amplitude P waves of the surface ECG can potentially serve as screening tool to identify hypertensive patients at risk of future AF episodes.

AimsHypertension is a major risk factor for atrial fibrillation (AF); however, reliable non-invasive tools to assess AF risk in hypertensive patients are lacking. We sought to evaluate the efficacy of P wave wavelet analysis in predicting AF risk recurrence in a hypertensive cohort.MethodsWe studied 37 hypertensive patients who presented with an AF episode for the first time and 37 age- and sex-matched hypertensive controls without AF. P wave duration and energy variables were measured for each subject [i.e. mean and max P wave energy along horizontal (x), coronal (y) and sagittal (z) axes in low, intermediate and high frequency bands]. AF-free survival was assessed over a follow-up of 12.1 ± 0.4 months.ResultsP wave duration (Pdurz) and mean P wave energy in the intermediate frequency band across sagittal axis (mean2z) were independently associated with baseline AF status (p = 0.008 and p = 0.001, respectively). Based on optimal cut-off points, four groups were formed: Pdurz < 83.2 ms/mean2z < 6.2 μV2 (n = 23), Pdurz < 83.2 ms/mean2z ≥ 6.2 μV2 (n = 10), Pdurz ≥ 83.2 ms/mean2z < 6.2 μV2 (n = 22) and Pdurz ≥ 83.2 ms/mean2z ≥ 6.2 μV2 (n = 19). AF-free survival decreased (Log Rank p < 0.0001) from low risk (Pdurz < 83.2 ms/mean2z < 6.2 μV2) to high-risk group (Pdurz ≥ 83.2 ms/mean2z ≥ 6.2 μV2). Patients presenting with longer and higher energy P waves were at 18 times higher AF risk compared to those with neither (OR: 17.6, 95% CI: 3.7-84.3) even after adjustment for age, sex, hypertension duration, left atrial size, beta-blocker, ACEi/ARBs and statin therapy.ConclusionsP wave temporal and energy characteristics extracted using wavelet analysis can potentially serve as screening tool to identify hypertensive patients at risk of AF recurrence.