8 Diagnostic performance of ECG detection of left atrial enlargement in patients with arterial hypertension relative to the cardiac magnetic resonance gold-standard: Impact of obesity

ECG may demonstrate evidence of left atrial enlargement (LAE), which has adverse prognostic implications. We sought to determine the accuracy of 5 ECG criteria of LAE in a hypertensive cohort relative to CMR and to investigate the confounding effect of obesity.MethodsConsecutive referrals for CMR from a tertiary hypertension clinic were reviewed. Patients with any concomitant cardiac pathology were excluded. ECGs were assessed, blinded to CMR data, for: 1) P wave >110ms, 2) P-mitrale (notched P wave with inter-peak duration >40ms), 3) P wave axis 40ms•mm and 5) Positive P terminal force in aVL (PPTF-aVL) >0.5mm. Maximal LA volume index (LAVI) was measured by the biplane area-length method.Abstract 8 Table 1A) Diagnostic performance of the various ECG parameters at detecting left atrial enlargement; B) Obesity subgroup analysis of diagnostic performance of the various ECG parameters at detecting left atrial enlargement A) Diagnostic performance of the various ECG parameters Prevalence ECG LAE (%) ROC-AUC (95th CI) Sensitivity (%) Specificity (%) PPV (%) NPV (%) ACC (%) P > 110 ms 90.497 (0.384 – 0.610)991257469 P mitrale 10.495 (0.382 – 0.608)09907473 P axis < 30o 270.437 (0.328 – 0.546)1870177156 NPTF-V1 > 40 ms.mm 170.465 (0.355 – 0.576)1281187263 PPTF-aVL > 0.5 mm 80.502 (0.389 – 0.616)992277470 Any ECG criteria for LAE 460.387 (0.279 – 0.495)2948176543 B) Subgroup analysis by obesity P > 110 ms Non-obese100.515 (0.352 – 0.6791291337470Obese90.519 (0.357 – 0.681)1292337572 P mitrale Non-obese20.529 (0.364 – 0.695)09807473Obese00.500 (0.340 – 0.660)010007575 P axis < 30o Non-obese210.560 (0.395 – 0.725)2983387668Obese340.467 (0.309 – 0.625)2964227355 NPTF-V1 > 40 ms.mm Non-obese110.504 (0.342 – 0.667)1289297368Obese210.478 (0.320 – 0.636)1878217463 PPTF-aVL > 0.5 mm Non-obese60.537 (0.371 – 0.703)1296507573Obese100.469 (0.314 – 0.625)688147367 Any ECG criteria for LAE Non-obese410.620 (0.462 – 0.778)5965388163Obese510.475 (0.315 – 0.635)4748247348(LAE = left atrial enlargement, ROC-AUC = receiver operator curve-area under curve, CI = confidence interval, PPV = positive predictive value, NPV = negative predictive values, ACC = accuracy)Results130 patients were included (age: 51.4 ± 15.1 years, 47% male, 51% obese, systolic blood pressure: 171 ± 29 mmHg, diastolic blood pressure: 97 ± 15 mmHg). The prevalence of LAE by CMR was 26% and by ECG varied from 1% (P-mitrale) to 27% (P axis