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Notes: Introduction: This study evaluated the role of surface ECG in assessment of risk of new-onset atrial fibrillation (AF) after coronary artery bypass grafting surgery (CABG). Methods and Results: One hundred fifty-one patients (126 men and 25 women; age 65 ± 10 years) without a history of AF undergoing primary elective and isolated CABG were studied. Standard 12-lead ECGs and P wave signal-averaged ECG (PSAE) were recorded 24 hours before CABG using a MAC VU ECG recorder. In addition to routine ECG measurements, two P wave (P wave complexity ratio [pCR]; P wave morphology dispersion [PMD]) and six T wave morphology descriptors (total cosine R to T [TCRT]; T wave morphology dispersion of ascending and descending part of the T wave [aTMD and dTMD], and others), and three PSAE indices (filtered P wave duration [PD]; root mean square voltage of terminal 20 msec of averaged P wave [RMS20]; and integral of P wave [Pi]) were investigated. During a mean hospital stay of 7.3 ± 6.2 days after CABG, 40 (26%) patients developed AF (AF group) and 111 remained AF-free (no AF group). AF patients were older (69 ± 9 years vs 64 ± 10 years, P = 0.005). PD (135 ± 9 msec vs 133 ± 12 msec, P = NS) and RMS20 (4.5 ± 1.7 μV vs 4.0 ± 1.6 μV, P = NS) in AF were similar to that in no AF, whereas Pi was significantly increased in AF (757 ± 230 μVmsec vs 659 ± 206 μVmsec, P = 0.007). Both pCR (32 ± 11 vs 27 ± 10) and PMD (31.5 ± 14.0 vs 26.4 ± 12.3) were significantly greater in AF (P = 0.012 and 0.048, respectively). TCRT (0.028 ± 0.596 vs 0.310 ± 0.542, P = 0.009) and dTMD (0.63 ± 0.03 vs 0.64 ± 0.02, P = 0.004) were significantly reduced in AF compared with no AF. Measurements of aTMD and three other T wave descriptors were similar in AF and no AF. Significant variables by univariate analysis, including advanced age (P = 0.014), impaired left ventricular function (P = 0.02), greater Pi (P = 0.012), and lower TCRT (P = 0.007) or dTMD, were entered into multiple logistic regression models. Increased Pi (P = 0.038), reduced TCRT (P = 0.040), and lower dTMD (P = 0.014) predicted AF after CABG independently. In patients 〈70 years, a linear combination of increased pCR and lower TCRT separated AF and no AF with a sensitivity of 74% and specificity of 62% (P = 0.005). Conclusion: ECG assessment identifies patients vulnerable to AF after CABG. Combination of ECG parameters assessed preoperatively may play an important role in predicting new-onset AF after CABG.

Notes: Background: The prolongation of P-wave duration has long been shown to indicate the presence of high risk for atrial fibrillation. The circadian variation of P-wave characteristics and their dynamic adaptation to heart rate changes was not tested before.Methods: To evaluate the diurnal pattern of P-wave duration, P area, and PR interval and of their linearly fitted relation with RR interval, 50 healthy volunteers (25 men, mean age 34 ± 10 years) underwent 24-hour ambulatory electrocardiographic (ECG) recording with digital 12-lead Holter recorders. The median P-wave duration, P area, and PR interval were calculated from the average 12-lead ECG constructed from each 10-second ECC recording. Single harmonic regression analysis was performed to reveal the presence of circadian variation in the aforementioned ECG parameters.Results: The P area (P 〈 0.0001, R2= 0.78), the PR interval (P 〈 0.0001, R2= 0.92), the P area / RR slope (P 〈 0.0001, R2= 0.55), and the PR/RR slope (P 〈 0.0001, R2= 0.42) showed a highly significant circadian variation while the periodic nature of P-wave duration (P = 0.016, R2= 0.32) and of the P duration / RR slope (P = 0.011, R2= 0.18) was only indicated by harmonic regression analysis.Conclusions: P-wave duration, P area, and PR interval show a significant circadian variation in healthy subjects. The relations between P area/RR,PR/ RR, and P duration/RR also demonstrate a significant diurnal pattern. A.N.E. 2001;6(2):92–97

Notes: BATCHVAROV, V., et al.: Ventricular Gradient as a Risk Factor in Survivors of Acute Myocardial Infarction. The total cosine between R and T (TCRT) (angular difference between the spatial QRS and T wave loops) is a technical elaboration of the concept of ventricular gradient (VG), whose power as a risk stratifier in post-MI patients has already been demonstrated. Recently, it was reported that TCRT differed significantly between healthy men and women, which suggested that its predictive power might be gender dependent. The aim of the study was to investigate TCRT and its association with cardiac mortality in male and female survivors of acute MI. TCRT was measured from digital Frank orthogonal XYZ-lead ECGs recorded before hospital discharge in 681 survivors of acute MI (82% men, age: men 57.0 ± 8.4 years , women 59.6 ± 8.1 years, P = 0.002 ). During a follow-up censored at 5 years, cardiac mortality rates were 9.7% and 12.1% in men and women, respectively (P = 0.42) . There were no significant difference in TCRT between men and women ( −0.150 ± 0.704 vs −0.070 ± 0.731, P = 0.26 ). In univariate Cox regression analysis, TCRT 〈 −0.88 was related to a 5-year cardiac mortality in men (relative risk [RR] 3.67, 95% confidence interval [CI] 2.13–6.34, P = 1.9 × 10 −6 ), and women (RR 5.16, 95% CI 1.83–14.56, P = 0.0015) . Depressed TCRT was strongly associated with increased long-term cardiac mortality in survivors of acute MI. Its predictive power did not differ significantly between the sexes. The role of TCRT as a risk-stratifier in post-MI patients deserves further prospective assessment in multivariate models with established risk factors. (PACE 2003; 26[Pt. II]:373–376)