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.

The prolongation of intro-ahial and inter-&al conduction time and the inhomogeneous propagation of sinus impulses are characteristics of atrium prone to fibrillate which can be evaluated by P wave durations and P wave dispersion.Myocardial fibrosis is found in most sclerodema patients at autopsy.Therefore, in this study we aimed to determine atria1 conduction properties in patients with sclerodema by measurement of P wave durations and P wave dispersion.

A previous report on heart rate (HR) turbulence showed its value in postinfarction risk stratification. The present study determines the predictive value of HR turbulence in a low-risk population after acute myocardial infarction and provides insight into its pathophysiologic correlates. With use of the database of the The Autonomic Tone and Reflexes After Myocardial Infarction (ATRAMI) study, data were obtained from 1,212 survivors with a mean duration of follow-up of 20.3 months. The a priori end point was defined as the combination of fatal cardiac arrest and nonfatal cardiac arrest. HR turbulence characterized by turbulence onset (TO) and turbulence slope (TS) was calculated and correlated with baroreflex sensitivity (BRS) and the SD of the normal-to-normal RR intervals (SDNN). A composite index of cardiac autonomic function was assessed by combining HR turbulence (TO and TS), BRS, and SDNN. Both TO and TS correlated moderately but significantly with BRS and SDNN (r = 0.26 to 0.44, p <0.001 for all correlations). On Cox’s univariate regression analysis, the RRs for abnormal values of TO, TS, and the combination of abnormal TO and TS were 1.86 (95% confidence interval [CI] 0.96 to 3.61, p = 0.065), 4.08 (95% CI 2.11 to 7.89, p <0.0001), and 6.87 (95% CI 3.06 to 15.45, p <0.0001), respectively. The composite autonomic index (combined TO, TS, BRS, and SDNN) was the strongest risk predictor: for all 4 abnormal factors, RR 16.79 (95% CI 6.01 to 46.89, p <0.0001). On multivariate analysis, abnormal TO and TS, and left ventricular ejection fraction remained as independent predictors: RRs 4.07 (95% CI 1.70 to 9.77, p = 0.0017) and 3.53 (95% CI 1.76 to 7.06, p = 0.0004), respectively. In a separate model, the composite autonomic index was the strongest multivariate risk predictor: RR 8.67 (95% CI 2.72 to 7.65, p = 0.0003) for all abnormal factors, and adjusted for left ventricular ejection fraction. Thus, this study confirms the independent value of HR turbulence in predicting fatal cardiac arrest and nonfatal cardiac arrest in a low-risk post-acute myocardial infarction population. By combining HR turbulence, BRS, and SDNN, a comprehensive assessment of cardiac autonomic reflexes and modulation can be obtained.

Heart rate turbulence (HRT) describes a bi-phasic chronotropic response of sinus rhythm to a ventricular premature beat (VPB). The aim of the study was to investigate whether an atrial premature beat (APB) can produce HRT and whether it can be described using ventricular HRT quantifiers (turbulence onset, TO, and turbulence slope, TS). Methods: Thirty-seven subjects (54±16 years) referred for electrophysiologic evaluation for ventricular tachyarrhythmias underwent a stimulation protocol consisting of 3 series of single atrial and ventricular extrastimuli delivered from the high right atrium and right ventricular apex prior to programmed electrical stimulation. Atrial and ventricular TO and TS (ATO, ATS, VTO, VTS) were calculated separately using a dedicated computer algorithm. Results: Expressed as mean±SD, VTO -2.03±0.42%, ATO 1.37±0.35% (p <0.001); VTS 8.32±1.9 ms/RR, ATS 3.95±0.99 ms/RR (p <0.008). There was a strong correlation between VTS and ATS (r=0.71, p=0.0002; Figure, right) but not between VTO and ATO (r=0.83, p=0,074; left). Conclusions: HRT phenomenon is present after an APB, suggesting that similar baroreceptor mechanisms operate following both VPB and APB. After an APB, the late phase response (rhythm deceleration) is significantly attenuated and the early phase response is different than that after a VPB, indicating the presence of alternative mechanisms. Atrial HRT can be measured using existing technique but algorithm adjustments are desirable. ACC 2002 / 51st Annual Scientific Session March 17-20, 2002, Atlanta, Georgia, USA Page 1

Recently, it was demonstrated that the QT-RR relationship pattern varies significantly among healthy individuals. We compared the intra- and interindividual variations of the QT-RR relationship. Twenty-four-hour 12-lead digital electrocardiograms (ECGs; SEER MC, GE Marquette; 10-s ECG recorded every 30 s) were obtained at baseline and after 24 h, 1 wk, and 1 mo in 75 healthy subjects (42 women, 33 men, age 27.9+/-9.6 vs. 26.8+/-7.5 yr, P=not significant). QT interval was measured automatically in each ECG by six different algorithms, and the mean of the six measurements was analyzed. In each recording of each individual, QT-RR relationship was assessed by 10 different regression models including linear (QT = beta + alpha x RR) and parabolic (QT = beta x RRalpha) models. Standard deviations (SDs) of regression parameters alpha and beta of consecutive recordings of each individual were compared with SD of the individual means. Intrasubject stability and interindividual variability were further tested by ANOVA. With all models, intraindividual SDs of the regression parameters were highly significantly smaller than SD of individual means (P<10(-5)-10(-9)). The intrasubject stability was further confirmed by ANOVA (P < 10(-19)-10(-30)). The QT-RR relationship exhibits substantial intersubject variability as well as a high intrasubject stability. This has practical implications for a precise estimation of the heart rate-corrected QT interval in which optimized subject-specific rate correction formulas should be used.

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)

BACKGROUND:Total R T cosine (TCRT) is a new descriptor of repolarization heterogeneity that quantifies the deviation between the directions of ventricular depolarization and repolarization. It revives the old concept of ventricular gradient (VG). HYPOTHESIS:Our goal was to examine whether TCRT and VG contain nonredundant information by comparing their reaction to autonomic tests, namely, postural changes and Valsalva maneuver. METHODS:Digital 12-lead electrocardiograms were recorded in 16 patients with cardiovascular syndrome X (SX, chest pain, exercise-induced ST-depression, normal coronary arteries, 3 men, age 60 +/- 9 years) and 40 healthy volunteers (31 men, age 33 +/- 7 years) during postural changes and Valsalva maneuver. The angle (VGA) [degrees] and magnitude (VGM) [ms.mV] of VG in reconstructed XYZ leads and TCRT (average cosine of the angles between the QRS and T vectors in mathematically reconstructed three-dimensional space) were calculated. RESULTS:(mean +/- standard of the mean): In healthy subjects, VGM and TCRT decreased, whereas VGA increased in the sitting and standing compared with supine position (TCRT: 0.61 +/- 0.05,0.47 +/- 0.06,0.29 +/- 0.08, supine, sitting, and standing, p < 0.05) and during phase II Valsalva (TCRT: 0.47 +/- 0.06 vs. 0.61 +/- 0.05, p < 0.01 in supine, 0.24 +/- 0.08 vs. 0.37 +/- 0.07, p < 0.01 in standing). In patients with SX, VGM decreased in the standing position, VGA did not change significantly, while TCRT decreased only in patients without T-wave abnormalities (n = 9) (TCRT in standing and supine: 0.55 +/- 0.09 vs. 0.68 +/- 0.08, p < 0.05). VG(M) increased during Valsalva in patients with SX. Total R T cosine correlated strongly with VGA (r = -0.84, p < 0.00001) and, unlike VGM, did not correlate with heart rate. CONCLUSIONS:Ventricular gradient and TCRT contain nonredundant information. In healthy subjects, they react sensitively to autonomic provocation. In patients with SX, their reaction is attenuated, which suggests disturbance of the autonomic control of repolarization.

The consumption of recreational drugs has reached epidemic proportions. Forty five million European Union citizens have used cannabis at some time, with proportionately higher use among younger people.1 The consumption of harder drugs such as cocaine and heroin is rising, with an estimated 1.5 million problem users in the European Union. Drug use is commonly associated with complications, including an increased risk of premature death. 1 2 In particular, recreational drugs have profound effects on cardiovascular function. Some studies suggest that adverse cardiac events are relatively uncommon, 1 3-5 though recent data from the United States indicate that one in four myocardial infarcts in people aged 18-45 years can be linked to cocaine use, suggesting that variation in definitions may contribute to under-reporting. 1 6 Many physicians will encounter patients with cardiovascular problems related to recreational drug misuse. In addition to the problems posed by self administration, massive overdoses may occur in individuals who attempt to smuggle illegal drugs by ingesting packets which rupture in the gastrointestinal tract; and inadvertent ingestion of recreational drugs by children has been reported. …

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 ECG 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, R(2) = 0.78), the PR interval (P < 0.0001, R(2) = 0.92), the P area / RR slope (P < 0.0001, R(2) = 0.55), and the PR/RR slope (P < 0.0001, R(2) = 0.42) showed a highly significant circadian variation while the periodic nature of P-wave duration (P = 0.016, R(2) = 0.32) and of the P duration / RR slope (P = 0.011, R(2) = 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.