Hisaaki Mera

The Full Stomach Test as a Novel Diagnostic Technique for Identifying Patients at Risk of Brugada Syndrome

Introduction: Autonomic modulation, particularly high vagal tone, plays an important role in the occurrence of ventricular tachyarrhythmias in the Brugada syndrome. Food intake modulates vagal activity. We assessed the usefulness of a novel diagnostic technique, the “full stomach test,” for identifying a high‐risk group in patients with a Brugada‐type electrocardiogram (ECG).

Circadian variation of late potentials in idiopathic ventricular fibrillation associated with J waves: Insights into alternative pathophysiology and risk stratification

BACKGROUND The presence of J waves on ECGs is related to idiopathic ventricular fibrillation (VF). OBJECTIVE The purpose of this study was to investigate the pathophysiology of J waves by assessing risk markers that reflect electrophysiologic abnormalities. METHODS The study enrolled 22 idiopathic VF patients (17 men and 5 women; mean age 36 +/- 13 years). Patients were divided into two groups according to the presence or absence of J waves. The following risk stratifiers were assessed: late potentials (LPs; depolarization abnormality marker) for 24 hours using a newly developed signal-averaging system, and T-wave alternans and QT dispersion (repolarization abnormality markers). Frequency-domain heart rate variability (HRV), which reflects autonomic modulation, also was assessed. The results were compared to those of 30 control subjects with J waves and 30 with no J wave, matched for age and gender to the idiopathic VF patients. RESULTS J waves were present in 7 (32%) idiopathic VF patients. The incidence of LP in the idiopathic VF J-wave group was higher than in the idiopathic VF non-J-wave group (86% vs 27%, P = .02). In contrast, repolarization abnormality markers did not differ between the two groups. In the idiopathic VF J-wave group, dynamic changes in LP parameters (fQRS, RMS(40), LAS(40)) were observed and were pronounced at nighttime; this was not the case in the idiopathic VF non-J-wave group and the control J-wave group. High-frequency components (vagal tone index) on frequency-domain HRV analysis were associated with J waves in idiopathic VF patients (P < .05). CONCLUSION Idiopathic VF patients with J waves had a high incidence of LP showing circadian variation with night ascendancy. J waves may be more closely associated with depolarization abnormality and autonomic modulation than with repolarization abnormality.

Time-domain T-wave alternans measured from Holter electrocardiograms predicts cardiac mortality in patients with left ventricular dysfunction: A prospective study

BACKGROUND Time-domain T-wave alternans (TWA) is useful for identifying patients at risk for serious events after myocardial infarction. OBJECTIVE The purpose of this study was to prospectively evaluate the utility of time-domain TWA measured from Holter ECGs in predicting cardiac mortality in patients with left ventricular (LV) dysfunction. METHODS Two hundred ninety-five consecutive patients with LV dysfunction were enrolled in the study. Patients were divided into two groups: the ischemic group (n = 195) and the nonischemic group (n = 100). Time-domain TWA was assessed using the modified moving average method from routine 24-hour Holter ECGs recorded during daily activity. The maximal time-domain TWA voltage at heart rate <or=120 bpm in either lead V(5) or V(1) was derived and its value defined as positive when the voltage was >or=65 microV. The primary end-point was defined as cardiac mortality. RESULTS Mean maximal time-domain TWA voltage was 54 +/- 16 microV. During follow-up of 390 +/- 212 days, 27 patients (17 in the ischemic group and 10 in the nonischemic group) died of cardiac causes. Fifty-three patients (18%) were time-domain TWA positive and 242 (82%) were time-domain TWA negative. Univariate Cox proportional hazards analyses revealed that older age, New York Heart Association functional class III or IV, diabetes, renal dysfunction, nonsustained ventricular tachycardia, and time-domain TWA were associated with cardiac mortality. In multivariate analysis, time-domain TWA had the most significant value (hazard ratio = 17.1, P <.0001). This index also was significant in both subgroups (ischemic group: hazard ratio = 19.0, P <.0001; nonischemic group: hazard ratio = 12.3, P = .002). CONCLUSION Time-domain TWA measured from 24-hour Holter ECGs predicts cardiac mortality in patients with ischemic and nonischemic LV dysfunction.

High-sensitivity cardiac troponin T for earlier diagnosis of acute myocardial infarction in patients with initially negative troponin T test--comparison between cardiac markers.

BACKGROUND AND PURPOSE An early diagnosis is essential for therapeutic decision and risk stratification in patients with suspected acute myocardial infarction (AMI). We analyzed and compared the diagnostic value of high-sensitivity troponin T (hs-TnT) and other cardiac markers in patients with an initially negative troponin T test at presentation. METHODS AND SUBJECTS The present study was a prospective, multicenter study including five participating emergency cardiovascular tertiary centers in Japan. From November 2009 through January 2011, patients with suspected AMI at the emergency room with an initial troponin T (c-TnT) test <100 ng/L were enrolled. RESULTS A total of 85 patients were prospectively assigned from five participating emergency cardiovascular tertiary centers in Japan. The median time from the onset of chest pain to the T0 sampling was 165 min [IQR 120-180]. The final diagnoses according to the recent universal definition and other standard cut-off values were AMI in 47, unstable angina in 12, and non AMI in 38 patients. The overall ROC-AUC value of hs-TnT, c-TnT, creatine kinase MB, and heart-type fatty acid-binding protein were 0.810, 0.716, 0.782, and 0.880, respectively. The diagnostic sensitivity and negative predictive value of hs-TnT were both 100% for the patients admitted more than 120 min from the onset, however the specificity was limited for the whole time-windows (71%). The absolute value change of the hs-TnT from T0 to T3 sampling 3h later improved the ROC-AUC up to 0.972 and the specificity was 92% at 22 ng/L (ROC-optimized cut-off) and 100% at 105 ng/L (rule-in cut-off). CONCLUSIONS The hs-TnT displayed 100% sensitivity and negative predictive value for the patients admitted more than 120 min from the onset, however the specificity was limited. The absolute change from T0 to T3 (22 ng/L) improved the total diagnostic performance.

Quantitative assessment of cibenzoline administration for vagally mediated paroxysmal atrial fibrillation using frequency-domain heart rate variability analysis

BACKGROUND Cibenzoline (CBZ), a class I antiarrhythmic drug, has been widely used to maintain sinus rhythm in patients with paroxysmal atrial fibrillation (P-AF). This agent has an anticholinergic action and will become the drug of first choice for vagally mediated P-AF. We assessed its efficacy quantitatively by analyzing the frequency-domain heart rate variability (FD-HRV) of the Holter electrocardiogram (ECG) in patients with vagal P-AF. METHODS We enrolled 65 consecutive patients with vagal P-AF, but 31 patients were excluded because of the occurrence of significant arrhythmias during the 24-h Holter recordings. Accordingly, CBZ was administered to the remaining 34 patients. After administration, a Holter ECG recording was made again. High frequency (HF) components, i.e., vagal tone index, on the FD-HRV analysis from 00:00 h to 06:00 h were used for assessment. In 14 patients, the treatment was changed to disopyramide (DSP) and the same analyses were performed. RESULTS In two patients, the FD-HRV analysis was not utilized after administration. Finally, 32 patients were available for evaluation. CBZ was considered effective for vagal P-AF in 24 patients (75%). After administration, the HF component levels decreased (1589+/-795 ms(2) vs. 850+/-524 ms(2), p<0.0001). Comparison of the pre-administration HF component levels between the CBZ-responsive group and the CBZ-non-responsive group showed higher levels in the CBZ-responsive group (1766+/-758 ms(2) vs. 1058+/-690 ms(2), p=0.026). Although no significant difference in the reduction of the HF component levels was found between CBZ and DSP, DSP had anticholinergic side effects in two patients (14%). CONCLUSIONS In vagal P-AF patients, larger HF components on the FD-HRV analysis could be a hallmark of the antiarrhythmic action of CBZ. The reduction in the HF component levels after drug administration is useful for a quantitative assessment of anticholinergic action.

NEW STRATEGY OF MEDICAL THERAPY TO LEFT VENTRICULAR DYSFUNCTION WITHOUT SIGNIFICANT CORONARY STENOSIS BY USING ACETYLCHOLINE PROVOCATION

Results: In either patient with positive ACh-test (n=13) or with negative ACh-test (n=19), LV function was severely depressed (LVEF: 32 vs. 37%, ns; BNP: 903 vs. 580; ns). In all of patients with positive ACh-test, ACh-CAG showed multi-vessel diffuse coronary spasm with remarkable ECG changes. Among positive ACh-test group, all of three LV biopsy specimens were negative, and only one of 10 cases (10%) showed an abnormal MRI delayed enhancement (DE). On the other hand, among the negative ACh-test group, LV biopsy in 2 of 3 cases and MRI-DE findings in 5 of 10 cases showed more frequently abnormal findings compatible with cardiomyopathy than among the positive ACh-test group (60%, vs. 10%, p<0.05). Among the positive ACh-test group, depressed LV function improved after starting Ca antagonist during 3 months (LVEF: 32±12% to 49±13%, p<0.01; BNP: 903±565 to 80±40, p<0.01), however, among the negative ACh-test group, depressed LV improved under treatment of antagonist during 8 months (LVEF: 37±11% to 44±11%, p<0.01; BNP: 580±470 to 144±149, p<0.01).