EUS-guided choledochoduodenostomy for palliative biliary drainage in patients with malignant biliary obstruction: results of long-term follow-up.

Five patients with obstructive jaundice caused by malignant periampullary biliary stenosis underwent EUS-guided choledochoduodenostomy (EUS-CDS) from the first portion of the duodenum using a convex echoendoscope and a needle knife. All the steps of the procedure including passage dilatation and the plastic stent placement were performed through the accessory channel of the echoendoscope over the guide wire. Stent insertion was technically successful in all five patients. The procedure was also clinically effective in relieving jaundice in all cases. One patient developed pneumoperitoneum, which resolved with conservative management. Stent exchange was successful in seven of eight attempts in patients with stent occlusion. One failure was due to tumor invasion to the choledochoduodenal fistula. Stent patency was maintained in the remaining patients throughout their survival period. The average stent patency was 211.8 days. EUS-CDS from the first portion of the duodenum appears to be feasible and safe in cases of obstructive jaundice caused by distal bile duct obstruction.

Prognostic significance of cardiac (123)I metaiodobenzylguanidine imaging for mortality and morbidity in patients with chronic heart failure: a prospective study.

OBJECTIVE: To determine whether cardiac iodine-123 metaiodobenzylguanidine ((123)I MIBG) imaging is useful in predicting the prognosis of patients with chronic heart failure. DESIGN: Cardiac (123)I MIBG imaging was done on entry to the study. The cardiac MIBG washout rate was calculated from anterior chest view images obtained 20 and 200 minutes after injection of the isotope. Study patients were divided into two groups with washout rates above and below 27% (the mean value + 2 SD obtained in 20 normal subjects), and were then followed up. SETTING: Tertiary referral centre. PATIENTS: 79 patients with chronic heart failure in whom the left ventricular ejection fraction was less than 40%. RESULTS: There were 37 patients in group 1 (washout rate of >/= 27%) and 42 in group 2 (< 27%). During a follow up period of between 1 and 52 months, eight patients died suddenly and five died of worsening heart failure in group 1, while none died in group 2; 13 patients in group 1 and four in group 2 were admitted to hospital for progressive heart failure. Kaplan-Meier analysis showed that group 1 had a significantly higher mortality and morbidity (p = 0.001 and p < 0.001, respectively) than group 2. CONCLUSIONS: Cardiac (123)I MIBG washout rate seems to be a good predictor of prognosis in patients with chronic heart failure.

Identification of sinus node dysfunction by use of P-wave signal-averaged electrocardiograms in paroxysmal atrial fibrillation: a prospective study.

BACKGROUND: In patients with paroxysmal atrial fibrillation (Paf), the identification of the coexistence of sinus node dysfunction (SND) has therapeutic implications. This study sought to prospectively determine whether SND in patients with Paf would be identified by use of atrial early potential (EP), low-amplitude potentials early in signal-averaged P wave. METHODS: The study population consisted of 149 patients with Paf. Signal-averaged electrocardiography was recorded with the P-wave-triggering technique. The root mean square voltage for the initial 30 MS and the duration of initial low-amplitude signals < 4 microV of signal-averaged P wave were measured in the vector magnitude. The criteria of EP were defined as "the root mean square voltage for the initial 30 MS < 3.0 microV and the duration of initial low-amplitude signals < 4 microV >22 MS." SND was diagnosed by use of the conventional 12-lead electrocardiography, 24-hour Holter monitoring, and bedside electrocardiographic monitoring. RESULTS: Thirty-eight of 149 patients with Paf had EP. Eighteen (47%) of 38 patients with Paf and EP had SND, whereas SND was found in only 5 (5%) of the other 111 patients with Paf without EP (P <.0001). EP gave a sensitivity of 78% and a specificity of 84% for the detection of SND in patients with Paf. CONCLUSION: EP would be useful for the identification of SND in patients with Paf.

Identification of 187 single nucleotide polymorphisms (SNPs) among 41 candidate genes for ischemic heart disease in the Japanese population.

To investigate whether common variants in the human genetic background are associated with pathogenesis of ischemic heart diseases, we systematically surveyed 41 possible candidate genes for single-nucleotide polymorphisms (SNPs) by directly sequencing 96 independent alleles at each locus, derived from 48 unrelated Japanese patients with myocardial infarction, including 25.8 kb 5' flanking regions, 56.8 kb exonic and 35.4 kb intronic sequences, and 1.8 kb 3' flanking regions. In this genomic DNA of nearly 120 kb, we identified 187 SNPs: 55 in 5' flanking regions, seven in 5' untranslated regions (UTRs), 52 in coding elements, 64 in introns, eight in 3' UTRs, and one in a 3' flanking region. Among the 52 coding SNPs, 26 were non-synonymous changes. Allelic frequencies of some of the polymorphisms were significantly different from those reported in European populations. For example, the Q506R substitution in the coagulation factor V gene, the so-called "Leiden mutation", has a reported frequency of 2.3% in Europeans, but we detected the Leiden mutation in none of the Japanese genomes that we investigated. The allelic frequencies of the -33A>G SNP in the thrombomodulin gene were also very different; this allele occurred at a 12% frequency in the Japanese patients that we examined, although it had been detected in none of 82 Caucasians reported previously. These data support the hypothesis that some SNPs are specific to particular ethnic groups.

Prediction of paroxysmal atrial fibrillation in patients with congestive heart failure: a prospective study.

OBJECTIVES: We sought to prospectively determine whether patients with congestive heart failure (CHF) at risk for paroxysmal atrial fibrillation (PAF) could be identified by clinical and study variables including the P-wave signal-averaged electrocardiogram (P-SAECG). BACKGROUND: Although it is important to assess the risk of developing PAF in patients with CHF, it still remains difficult to predict the PAF appearance in patients with CHF clinically. METHODS: The study group consisted of 75 patients in sinus rhythm without a history of PAF, whose left ventricular ejection fraction, as measured by radionuclide angiography, was <40%. These patients underwent P-SAECG, echocardiography and 24-h Holter monitoring; in addition, the plasma concentration of atrial natriuretic peptide (ANP) was measured at study entry. RESULTS: An abnormal P-SAECG was found at study entry in 29 of 75 patients. In the follow-up period of 21 +/- 9 months, the PAF attacks documented on the ECG significantly more frequently occurred in patients with (32%) rather than without an abnormal P-SAECG (2%) (p = 0.0002). The plasma ANP level was significantly higher in patients with rather than without PAF attacks (75 +/- 41 vs. 54 +/- 60 pg/ml, p = 0.01), although there were no significant differences in age, left atrial dimension or high grade atrial premature beats between the groups. The multivariate Cox analysis identified that the variables significantly associated with PAF development were an abnormal P-SAECG (hazard ratio 19.1, p = 0.0069) and elevated ANP level > or =60 pg/ml (hazard ratio 8.6, p = 0.018). CONCLUSIONS: An abnormal P-SAECG and elevated ANP level could be predictors of PAF development in patients with CHF.

Dispersion of signal-averaged P wave duration on precordial body surface in patients with paroxysmal atrial fibrillation.

AIMS: This study sought to investigate whether the spatial dispersion of signal-averaged P wave duration would be increased in patients with paroxysmal atrial fibrillation, by use of precordial mapping of the P wave signal-averaged ECG. METHODS AND RESULTS: The P wave signal-averaged ECG was recorded by the P wave-triggering method from 16 precordial leads in 55 patients with paroxysmal atrial fibrillation and 57 control subjects. As an index of the dispersion of signal-averaged P wave duration, we obtained the difference between the maximum and minimum in 16 recording sites. The dispersion was significantly greater in the patients with paroxysmal atrial fibrillation than the controls (26.6 +/- 9.5 vs 14.8 +/- 6.7 ms, P<0.0001). In 25 patients with symptomatic attacks of paroxysmal atrial fibrillation, the signal-averaged ECG was repeated 1 h after a single dose of orally administered pilsicainide, a new class Ic drug. These patients were prospectively followed-up for 10 +/- 11 months with pilsicainide. The rate of freedom from recurrence of paroxysmal atrial fibrillation attacks was significantly (P<0.0001) higher in patients with whom dispersion was decreased by the single dose (54%[7/13]) than in those in whom dispersion increased (8%[1/12]). CONCLUSION: Increased dispersion of signal-averaged P wave duration would play an important role in generating paroxysmal atrial fibrillation and would be useful in the prediction of drug efficacy to evaluate the change in dispersion by a single administration of pilsicainide.

Increased expression of P-selectin on platelets is a risk factor for silent cerebral infarction in patients with atrial fibrillation: role of nitric oxide.

BACKGROUND: Platelet activation and decreased levels of nitrite and nitrate (NOx), stable end products of nitric oxide (NO), are reported in patients with atrial fibrillation (AF). We examined the time-course changes in plasma NOx levels and the expression of P-selectin on platelets after the onset of AF in a canine model and determined whether these parameters could be risk factors for silent cerebral infarction in patients with AF. METHODS AND RESULTS: AF was induced by rapid atrial pacing in the canine model of AF. Plasma NOx levels were significantly decreased and the levels of P-selectin on platelets and of neutrophil/platelet conjugates were significantly increased after the onset of AF in this model. The in vitro experiments demonstrated that the inhibition of NO synthesis increased the expression of P-selectin on platelets. Plasma NOx levels (19.7+/-2.4 versus 27.5+/-2.8 micromol/L) were significantly lower in 25 patients with AF compared with age- (+/-2 years) and sex-matched control subjects. Conversely, the levels of P-selectin on platelets (7.6+/-0.8% versus 4.8+/-0.7%) and of neutrophil/platelet conjugates (14.8+/-0.9% versus 8.1+/-0.6%) were significantly higher in patients with AF. Multiple regression analysis revealed that increased P-selectin on platelets and advanced age were associated with the number of foci of silent cerebral infarction. CONCLUSIONS: An irregular heart rate that is characteristic of AF appeared to blunt NO synthesis. The increased expression of P-selectin on platelets associated with the reduced NO levels was a risk factor for silent cerebral infarction in patients with AF.

Prediction of the effectiveness of long-term beta blocker treatment for dilated cardiomyopathy by signal averaged electrocardiography.

OBJECTIVE: To determine whether the effectiveness of long-term beta blocker treatment for idiopathic dilated cardiomyopathy can be predicted by signal averaged electrocardiography (ECG). PATIENTS: 31 patients with dilated cardiomyopathy and without bundle branch block were included in a retrospective study and 16 in a prospective study. METHODS: A signal averaged ECG was recorded before beta blocker treatment, and three variables were measured from the vector magnitude: QRS duration, root mean square voltage for the last 40 ms (RMS40), and duration of the terminal low amplitude signals (< 40 microV) (LAS40). In the retrospective study, these variables were compared among good responders (showing > or = 0.10 increase in ejection fraction 12 months after start of beta blocker treatment) and poor responders without such improvement. The validity of the signal averaged ECG criteria for prediction of the response to beta blocker treatment was examined in the prospective study. RESULTS: In the retrospective study, good responders (n = 16) had a shorter QRS duration (mean (SD): 122.9 (11) v 138 (14.4) ms, p < 0.005) and LAS40 (33.1 (8.9) v 42.5 (7.8) ms, p < 0.005), and a higher RMS40 (31.6 (16.3) v 19.0 (10.3) microV, p < 0.02) than poor responders (n = 15). Signal averaged ECG criteria for good response were defined as two or more of the following: QRS duration < 130 ms, RMS40 > 20 microV, LAS40 < 40 ms (sensitivity 81%, specificity 73%). In the prospective study, six of seven patients who met these criteria showed a good response to the beta blocker treatment, while eight of nine who did not showed a poor response (chi 2 = 6.1, p < 0.02). The signal averaged ECG criteria gave a sensitivity of 86% and a specificity of 89% for predicting the effectiveness of beta blocker treatment. CONCLUSIONS: A signal averaged ECG might be useful in predicting the effectiveness of beta blocker treatment for dilated cardiomyopathy.

Prediction of transition to chronic atrial fibrillation in patients with paroxysmal atrial fibrillation by signal-averaged electrocardiography: a prospective study.

BACKGROUND: It is well known that paroxysmal atrial fibrillation (PAF) often precedes the establishment of chronic atrial fibrillation (CAF). However, there have been no definite methods to predict the transition from PAF to CAF. The purpose of this report was to determine prospectively whether P-wave-triggered signal-averaged ECG (P-SAE) is useful for the prediction of the transition to CAF in patients with PAF. METHODS AND RESULTS: One hundred twenty-two consecutive patients with PAF were prospectively followed after P-SAE, echocardiography, and 24-hour Holter monitoring at study entry. The duration (Ad) and root-mean-square voltage for the last 30 ms (LP30) of the filtered P wave were measured in P-SAE. The abnormality of P-SAE for the prediction of transition to CAF was defined as Ad > or = 145 ms and LP30 < 3.0 microV. Twenty-three (19%; group 1) of the patients had the abnormality of P-SAE, whereas the others (group 2) did not. During the follow-up period (mean, 26+/-12 months), 10 patients (43%) in group 1 acquired CAF, whereas the transition to CAF was observed in only 4 patients (4%) in group 2. Kaplan-Meier analysis revealed that the transition to CAF was significantly observed more often in group 1 than in group 2 (log-rank test, P<.0001). The Cox proportional hazards regression model identified that the variables most significantly associated with the transition to CAF were Ad (chi2=8.6, P=.003) and LP30 (chi2=5.1, P=.02), although significant differences in the left atrial dimension (40.8+/-5.3 versus 37.3+/-5.5 mm, P<.01) and the number of atrial premature contractions (3641+/-4524 versus 1489+/-2895 beats/d, P<.05) were observed between groups 1 and 2. CONCLUSIONS: These results indicate that P-SAE could be useful to identify patients at risk for the transition from PAF to CAF.

An approach to the detection of autonomic neuropathy by use of signal-averaged electrocardiography.

The beat-to-beat variation of PR interval, which is thought to be a reflection of autonomic nervous system, is difficult to measure with accuracy because the variation is too subtle. However, R wave amplitude in the P wave triggered SAECG is easily attenuated in comparison to that in the R wave triggered SAECG, which might be due to PR interval fluctuation. To determine whether autonomic neuropathy could be detected by use of SAECG, two types of SAECGs triggered by P and R waves were recorded in 23 diabetics with autonomic neuropathy and 41 age matched controls. The peak voltage of filtered QRS complex was measured in the R wave and P wave triggered SAECGs. Percent attenuation of the filtered QRS voltage was calculated by dividing the difference between the voltages in the R wave and P wave triggered SAECGs by the voltage in R wave triggered SAECG. The percent attenuation of filtered QRS voltage was significantly smaller in diabetics with autonomic neuropathy than controls (4.6% +/- 4.9% vs 16.3% +/- 15.0%; P < 0.001). These results suggest that the degree of attenuation of filtered QRS voltage in the P wave triggered SAECG would be useful for the detection of autonomic neuropathy.

Presence of poorly stained myocytes in acute myocarditis predicts improvement in cardiac function.

Histological findings in the acute phase of myocarditis were evaluated as a prediction of hemodynamic state in the chronic phase in 20 patients with clinical and pathological diagnoses of myocarditis who were followed up with echocardiography for at least 1 year. Endomyocardial biopsy samples were obtained from the left ventricle within 1 year of the onset of symptoms. Azan-Mallory staining was performed on the myocytes, which were categorized as either well stained or poorly stained. The point counting method was used to determine the fraction of each type. The improvement in ejection fraction within 1 year correlated significantly with the fraction of poorly stained myocytes (r = 0.46, p < 0.05). The ejection fraction at biopsy was negatively correlated with the volume fraction of well stained myocytes (r = -0.64, p < 0.01). The staining condition of myocytes may be useful in predicting the hemodynamic recovery of patients with myocarditis.

Detection of patients with sick sinus syndrome by use of low amplitude potentials early in filtered P wave.

OBJECTIVES: This study sought to determine whether patients with sick sinus syndrome could be detected by analyzing the initial portion of the signal-averaged P wave corresponding to the electrical activity of the perinodal atrial myocardial cells. BACKGROUND: In sick sinus syndrome, pathophysiologic abnormalities have been shown not only in the sinus node, but also in the atrial muscle, especially the perinodal portion. METHODS: The study included 41 patients with sick sinus syndrome and 140 age-matched control subjects. Eighteen of 41 patients with sick sinus syndrome had paroxysmal atrial fibrillation. Signal-averaged P wave electrocardiograms (ECGs) were recorded through a bandpass filter of 40 to 300 Hz with a P wave-triggering technique. Signals of the orthogonal bipolar leads were combined into a spatial magnitude. The root mean square voltage for the initial 30 ms (EP30) and the duration of initial low amplitude signals < 4 microV (ED4) of the filtered P wave were measured. The root mean square voltage for the last 20 ms (LP20) and the duration of the filtered P wave were also measured. RESULTS: EP30 was significantly lower and ED4 was significantly longer in patients with sick sinus syndrome than in the control subjects (EP30 [mean +/- SD]: 2.18 +/- 0.90 vs. 3.94 +/- 1.45 microV, p < 0.0001; ED4: 31.7 +/- 14.5 vs. 14.0 +/- 7.4 ms, p < 0.0001), although there was no significant difference in LP20 between patients with sick sinus syndrome without paroxysmal atrial fibrillation and the control subjects. The duration of the filtered P wave was significantly but minimally longer in patients with sick sinus syndrome than in the control subjects (139.8 +/- 18.8 vs. 127.3 +/- 13.6 ms, p < 0.0001). The criteria of EP30 < 3.0 microV and ED4 > 22 ms as atrial early potential gave a sensitivity of 76%, a specificity of 91%, a positive predictive value of 74% and a negative predictive value of 93% for identification of patients with sick sinus syndrome. CONCLUSIONS: These results suggest that the long, low amplitude signals early in the filtered P wave on the signal-averaged ECGs are characteristic of sick sinus syndrome. Thus, the atrial early potential could be a useful marker to identify patients with sick sinus syndrome.

[Noninvasive recording of pre-P wave related to sinus node electrical activity using P wave-triggered signal-averaging technique].

To determine whether the sinus node electrogram (SNE) could be detected noninvasively, a specially modified P wave-triggered signal-averaged electrocardiogram was recorded through the standard V1, V2 and V3 precordial leads in 39 patients. The data between 500 ms before and 300 ms after the trigger point were processed using a digital bandpass filter of 0.5 Hz (12 dB/oct)-20 Hz (18 dB/oct). Pre-P signals were observed just before the P wave resembling SNE recorded directly. Pre-P potential duration closely correlated with direct SACT (r = 0.856, P < 0.0005). Thus, it is believed that signals obtained by this new method would be related to sinus electrical activity and that it could be useful for noninvasive estimation of SACT.

[Spatial distribution of atrial late potentials on body surface mapping in patients with paroxysmal atrial fibrillation].

We investigated the spatial distribution of atrial late potentials (ALP) in patients with paroxysmal atrial fibrillation (Paf) by use of body surface signal-averaged ECG. The P wave-triggered signal-averaged ECG was recorded in 20 patients with Paf and 34 control patients from precordial 16 unipolar leads (standard V1-V6 and two intercostal spaces below and above V1, V2, V4-V6). The duration (Ad) and number of fragmented deflection (Nf) of filtered P wave were measured on each lead. % Area was also calculated by dividing the area for the last 20 msec by the total area of filtered P wave. The lead having any of a significantly longer Ad, larger Nf and smaller % Area in patients with Paf than the controls was designated as ALP positive lead. ALPs were observed in all other than two intercostal spaces above V5 and V6. This finding suggests that the electrophysiological disparity in the whole atrial muscle might be involved in patients with Paf.

Coronary atherosclerosis reduced in patients with familial hypercholesterolemia after intensive cholesterol lowering with low-density lipoprotein-apheresis: 1-year follow-up study. The Osaka LDL-Apheresis Multicenter Trial Group.

To test the hypothesis that aggressive cholesterol lowering results in a rapid regression of coronary atherosclerosis, the effect of low-density lipoprotein (LDL)-apheresis for 1 year on coronary artery diameters was studied in patients with heterozygous familial hypercholesterolemia. LDL-apheresis was performed every 2 weeks in 13 patients with LDL-cholesterol levels > or = 200 mg/dL despite treatment with conventional dietary and drug therapies. Coronary arteriography was performed before and 1 year after the initiation of treatment. The LDL-cholesterol level was decreased by an average of 71% immediately after the initial LDL-apheresis and by 30% before the second apheresis. Such phasic changes were observed throughout the trial. Computer-assisted automated quantitative arteriograms analyzed 101 proximal coronary segments. The mean lumen diameter of angiographically normal sections of each segment was slightly but significantly increased from 2.93 +/- 0.89 mm at baseline to 3.05 +/- 0.93 mm at the follow-up arteriogram (P < 0.05); 54 of the 101 segments showed a lesion stenosed by 20% or more in diameter. The minimal diameter of individual lesions was also significantly increased from 2.17 +/- 0.67 mm to 2.36 +/- 0.76 mm (P < 0.05), and thus the diameter stenosis was significantly reduced from 32.3 +/- 10.5% to 28.2 +/- 12.1% (P < 0.05). It is concluded that 1 year of aggressive cholesterol lowering, using LDL-apheresis, can significantly reduce coronary atherosclerosis in patients with familial hypercholesterolemia.

Long-term clinical effect of nilvadipine in patients with chronic heart failure: a double-blind placebo-controlled study.

The long-term effect of calcium channel blockers on chronic heart failure is disappointing, probably because of reflex sympathetic activation through arterial vasodilation. However, nilvadipine may be beneficial for treatment of chronic heart failure since this drug has minimal effects on sympathetic activation. In this study, the effects of 12-week administration of nilvadipine or placebo on symptoms of heart failure and cardiac function were investigated in 23 patients with mild-to-moderate chronic heart failure in a double-blind trial. The patients were randomly assigned to either a nilvadipine group (16 mg daily) or a placebo group. Intergroup comparisons did not show significant differences in any parameters. Serious adverse effects were not observed during the study. Thus, this study failed to show any beneficial effect of nilvadipine in the long-term treatment of patients with chronic heart failure. We conclude that the long-term administration of nilvadipine (16 mg daily) is neither effective nor harmful in the treatment of patients with chronic heart failure.

Dynamic process between the clotting and the lytic activities on intracardiac thrombi--its relationship with systemic embolization.

To clarify the relationship between clotting and lytic activities of intracardiac thrombi, and to elucidate whether this could be used to evaluate the embolic risk the ratio of indium-111 radioactivity accumulated on thrombi to that in the blood pool using dual-tracer technique %IE as a parameter of the clotting activity, and D-dimer, which is a fibrin specific degradation product, as a parameter of lytic activity were measured in 37 patients with intracardiac thrombi. Fifteen of the 37 patients had past histories of arterial embolization. The values of D-dimer correlated significantly with those of %IE (r = 0.758, p less than 0.01), e.g., the higher the values of D-dimer the higher the values of %IE. 37 patients were divided into 2 groups using the regression line for the D-dimer and %IE domains. Eleven patients above the regression line had thrombosis in excess of fibrinolysis but the remaining 26 patients under the regression line had fibrinolysis in excess of thrombosis. The incidence of past embolic episodes was 82% (9/11) in patients with thrombosis in excess of fibrinolysis but 23% (6/26) in patients with fibrinolysis in excess of thrombosis. These results demonstrated that intracardiac thrombi were under the dynamic process between the clotting and the lytic activities and moreover patients with intracardiac thrombi and thrombosis in excess of fibrinolysis had a substantial risk of arterial embolization.

Characteristics of frequency content of atrial signal-averaged electrocardiograms during sinus rhythm in patients with paroxysmal atrial fibrillation.

To clarify the characteristics of the frequency content of atrial signal-averaged electrocardiograms (ECGs) during sinus rhythm in patients with paroxysmal atrial fibrillation, P wave-triggered signal-averaged ECGs were recorded in 28 patients with and 34 control patients without paroxysmal atrial fibrillation. Fast Fourier transform analysis was performed on the 100-ms segment starting 75 ms before the end of the P wave. An area ratio (AR50) was calculated by dividing the area under the spectrum curve between 20 and 50 Hz, multiplied by 100, by the area between 0 and 20 Hz. Magnitude ratios (MR20, MR30, MR40 and MR50) were calculated by dividing the magnitude at 20, 30, 40 and 50 Hz, respectively, multiplied by 100, by the maximal magnitude of the entire signal. AR50 was significantly greater in patients with than without paroxysmal atrial fibrillation (62.3 +/- 34.2 vs. 42.4 +/- 18.4). MR20 and MR30 were also significantly greater in patients with than without paroxysmal atrial fibrillation (MR20 76.1 +/- 15.2 vs. 60 +/- 20.2; MR30 41 +/- 18.8 vs. 26.6 +/- 14.4), although no significant differences in MR40 or MR50 were observed between the two patient groups. The difference in MR30 between groups remained significant even after taking into account the presence of organic heart disease. It is concluded that, irrespective of the presence of organic heart disease, the terminal portion of the P wave contained significantly more components in the 20- to 50-Hz range, especially around 30 Hz, in patients with than in patients without paroxysmal atrial fibrillation. These results suggest that frequency analysis could characterize atrial signal-averaged ECGs of patients at risk for paroxysmal atrial fibrillation.