Prognostic implications of progressive cardiac conduction disease.

BACKGROUND: Progressive cardiac conduction disease (PCCD), characterized by temporal increase in PR interval and QRS duration, may be attributed to diverse pathophysiological mechanisms. This study aimed to investigate whether PCCD is associated with increased risk of cardiovascular morbidity and mortality. METHODS AND RESULTS: Digital analysis of 12-lead ECG was performed to select patients with PCCD from among a database containing 359,737 ECGs. Long-term prognosis of PCCD was assessed in a large hospital-based population: 458 patients (341 males; mean age, 57.9 ± 14.7 years) with PCCD were enrolled. During a mean follow-up of 13.3 ± 6.4 years, 109 patients were hospitalized for heart failure (HF), and there were 16 and 59 deaths from cardiovascular diseases and all causes, respectively. Multivariate Cox proportional hazards analysis confirmed (1) a significant association of temporal incremental rate of PR interval (≥ 2 ms/year) and QRS duration (≥ 3 ms/year) with HF hospitalization (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.36-4.05; P=0.002 and HR, 2.08; 95% CI, 1.25-3.53; P=0.01, respectively) and (2) a significant association of temporal incremental rate of PR interval (≥ 4 ms/year) and QRS duration (≥ 5 ms/year) with cardiovascular mortality (HR, 6.9; 95% CI, 1.47-36.96; P=0.02 and HR, 4.31; 95% CI, 1.19-16.5; P=0.03, respectively). CONCLUSIONS: The severity of PCCD was independently and significantly associated with HF hospitalization and cardiovascular mortality.

Risk determinants in individuals with a spontaneous type 1 Brugada ECG.

BACKGROUND: Spontaneous coved ST-segment elevation ≥2 mm followed by a negative T-wave in the right precordial leads (type 1 Brugada ECG) is diagnostic of Brugada syndrome (BS), but there is a false-positive rate. METHODS AND RESULTS: Computer-processed analysis of a 12-lead ECG database containing 49,286 females and 52,779 males was performed to select patients with a spontaneous type 1 Brugada ECG for an examination of the association of this ECG characteristic with long-term prognosis. There were 185 patients with a spontaneous type 1 Brugada ECG and of these, 16 (15 males; mean age, 46.7±14.0 years) were diagnosed with BS and 15 patients (all males; mean age, 50.1±13.4 years) were undiagnosed. The PQ interval was significantly longer in the diagnosed patients than in the undiagnosed patients (187.4±28.3 ms vs. 161.2±21.5 ms; P=0.0073). The T-wave in lead V(1) was more negative in the diagnosed patients than in the undiagnosed patients (-170.2±174.6 µV vs. -43.2±122.3 µV, P=0.027). Multivariate analysis revealed that a PQ interval ≥170 ms and T-wave amplitude <105 µV in lead V(1) were independent risk stratifiers of life-threatening events. Survival analysis (mean follow-up, 78.6±81.8 months) showed that the PQ interval and a negative T-wave in lead V(1) were significantly associated with poor prognosis. CONCLUSIONS: Analysis of a standard 12-lead ECG can stratify the prognosis of patients with a spontaneous type 1 Brugada ECG.

Association between brachial-ankle pulse wave velocity and endothelium-dependent and -independent coronary vasomotor function.

1. Coronary endothelial function and brachial-ankle pulse wave velocity (baPWV) are independent predictors of cardiovascular events. Thus, in the present study we examined the relationship between baPWV and endothelium-dependent and -independent coronary vasodilatory functions. 2. Sixty-five patients (12 diabetic and 53 non-diabetic) with no significant stenosis of the coronary artery were studied and baPWV determined. After cardiac catheterization, graded doses of bradykinin (BK; 0.2, 0.6 and 2.0 µg/min), nitroglycerin (NTG; 250 µg) and papaverine (Pa; 12 mg) were administered into the left anterior descending coronary artery. Coronary blood flow (CBF) was measured using a Doppler flow wire. 3. In the 65 patients, an inverse correlation was found between baPWV and the percentage change in epicardial coronary artery diameter (Δ%CoD), as well as the percentage change in CBF (Δ%CBF), following administration of BK (endothelium-dependent vasodilator). Moreover, inverse correlations were found between baPWV and Δ%CoD following administration of NTG (endothelium-independent vasodilator) and Δ%CBF following administration of Pa (endothelium-independent vasodilator). 4. Multivariate analysis revealed diabetes to be independently and significantly associated with baPWV, BK-induced Δ%CBF and Δ%CoD and Pa-induced Δ%CBF. 5. In conclusion, the results of the present study suggest that increased baPWV is associated with endothelium-dependent and -independent coronary vasodilatory dysfunction. Non-invasive and straightforward baPWV measurement may be useful for the assessment of coronary risk factors, particularly in diabetic patients.

Clinical features of myocardial triglyceride in different types of cardiomyopathy assessed by proton magnetic resonance spectroscopy: comparison with myocardial creatine.

BACKGROUND: Myocardial lipid overstorage may produce cardiomyopathy, leading to dysfunction, but advanced heart failure may cause lipolysis via sympathetic nerve activation. In the failing heart, the creatine kinase system may also be impaired. The aims of this study were to assess myocardial triglyceride (TG) and creatine (CR) in different types of cardiomyopathy and to investigate whether they are related to the severity of cardiac dysfunction. METHODS AND RESULTS: In patients with hypertrophic cardiomyopathy (HCM, n = 8), dilated cardiomyopathy (DCM, n = 12) or ischemic cardiomyopathy (ICM, n = 10), and normal subjects (NML, n = 22), myocardial TG and CR were evaluated using proton magnetic resonance spectroscopy. To assess cardiac sympathetic nerve activity, myocardial MIBG (a radioactive guanethidine analog) uptake was measured in DCM. Myocardial TG was significantly lower in hypertrophic cardiomyopathy (HCM) (1.92 ± 0.99 µmol/g), but higher in ICM (7.59 ± 4.36 µmol/g) than in NML hearts (4.05 ± 1.94 µmol/g). There was no significant difference in TG between DCM (4.84 ± 6.45 µmol/g) and NML. Myocardial CR in HCM (20.4 ± 8.4 µmol/g), DCM (14.8 ± 4.8 µmol/g), and ICM (19.4 ± 6.3 µmol/g) was significantly lower than that in NML hearts (27.1 ± 4.3 µmol/g). Overall, myocardial CR correlated positively with the severity of heart failure estimated by ejection fraction or myocardial BMIPP (a radioactive fatty acid analog) uptake, but TG did not. In DCM, myocardial TG correlated with body mass index, but not with MIBG uptake. CONCLUSIONS: Myocardial TG may be related to the specific cause of disease rather than the severity of cardiac dysfunction. In contrast, myocardial CR reflects the severity of heart failure despite different pathoetiologic mechanisms of dysfunction. In DCM, myocardial TG may be affected by an overweight state rather than cardiac sympathetic nerve dysfunction. Thus, myocardial CR has a closer relationship to heart failure severity than does myocardial TG.

The association between morning hypertension and metabolic syndrome in hypertensive patients.

Morning hypertension (MHT) and metabolic syndrome (MS) have been reported as important risk factors for stroke and cardiovascular events. We investigated the prevalence of MHT and MS among hypertensive patients in our outpatient clinic from June to August, 2005. We studied 181 hypertensive patients (91 men and 90 women) in our outpatient clinic using home-use electronic sphygmomanometers. Seventy-nine of these 181 patients (43.6%) demonstrated MHT, defined as systolic blood pressure (SBP) > or = 135 mmHg in the morning. Only 48.1% of the patients demonstrated normal SBP both at the clinic and in the morning at home, whereas 72.9% of the patients demonstrated normal diastolic blood pressure (DBP) under the same conditions. Sixty-one patients (33.7%) had MS, and 34 patients had both MHT and MS. Twenty-seven of the 102 patients (26.5%) without MHT had MS. The frequency of MS was significantly higher among those with MHT than those without MHT (p = 0.019). Multiple logistic regression analysis including smoking, alcohol consumption, sex, and age as confounding factors showed significant association between MHT and MS (odds ratio: 1.99; 95% confidence interval: 1.04-3.80; p = 0.039). In conclusion, although 1 year has passed since the JSH 2004 guidelines, 43.6% of our patients still showed MHT, and there was a significantly higher prevalence of MS among those with MHT. Our results suggest the need for a more vigorous intervention for controlling BP.

Clinical and electrocardiographic characteristics of patients with short QT interval in a large hospital-based population.

BACKGROUND: Short QT syndrome is one of the underlying disorders associated with ventricular fibrillation. However, the precise prognostic implication of a short QT interval remains unclear. OBJECTIVE: The purpose of this study was to investigate the prevalence and long-term prognosis in patients with a shorter-than-normal QT interval in a large hospital-based population. METHODS: We chose patients with a short Bazett QTc interval from a database consisting of 114,334 patients to determine the clinical characteristics and prognostic value of a short QT interval. RESULTS: A total of 427 patients (mean age 43.4 ± 22.4 years) had a short QT interval with about a 1.2 times higher male predominance (234 men). The QTc interval was significantly longer in female than in male patients (363.8 ± 6.1 ms vs 357.1 ± 5.8 ms, P <.0001). The age-specific prevalence of patients with short QT interval was biphasic, peaking at young and old age. Atrial fibrillation and early repolarization were complicated with short QT interval in 39 (9.1%) and 26 (6.1%) patients, respectively. The prognosis of 327 patients (182 men; mean age, 46.4 ± 27.3 years) with a short QT interval could be assessed (mean follow-up period, 54.0 ± 62.0 months). During the follow-up, 2 patients, 1 of whom had early repolarization, developed life-threatening events, in contrast to 6 patients who died of noncardiac causes and did not have early repolarization. CONCLUSION: The prevalence of a short QT interval showed a slight male preponderance and biphasic age-dependent distribution in both genders. The complication rate of atrial fibrillation was higher in those with a short QT interval than in general populations. The long-term outcome suggested that early repolarization in a short QT interval might be associated with potential risk of lethal arrhythmia.

Relationship between exercise capacity and cardiac diastolic function assessed by time-volume curve from 16-frame gated myocardial perfusion SPECT.

OBJECTIVE: Echocardiographic studies have suggested an association between diastolic dysfunction and exercise intolerance. The aim of this study was to examine the relationship between exercise capacity and left ventricular (LV) function during stress myocardial scintigraphy, and to investigate whether or not this relationship is caused by ischemia during exercise. METHODS: The studied patients underwent technetium-99m sestamibi quantitative gated SPECT, including treadmill exercise. Myocardial stress images were acquired 30 min after the first tracer injection (370 MBq) during maximal exercise. Three hours later, the second tracer (740 MBq) was injected, and resting images were acquired 30 min after this injection. The presence of ischemia was determined by tracer accumulation. From the same data source, LV diastolic parameters [first third filling fraction (1/3FF), first third filling rate (1/3FR), peak filling rate (PFR) and time to PFR (TPF)], and systolic parameters [ejection fraction (EF), peak ejection rate (PER), time to PER (TPE) and first third ejection fraction (1/3EF)] were analyzed. RESULTS: Subjects with exercise inability (<6 METs) were excluded. In 45 patients, diastolic parameters 1/3FF, 1/3FR, PFR and TPF correlated significantly with exercise duration (r = 0.32*, 0.37*, 0.37* and -0.40(#), respectively; *p < 0.05, (#) p < 0.01), but systolic parameters EF, PER, TPE and 1/3EF did not. At rest, 1/3FF, PFR and PER were significantly increased, suggesting functional deterioration during exercise. Even after 3 h, 1/3FR, PFR and TPF still correlated significantly with exercise duration (r = 0.29*, 0.36* and -0.30*, respectively; *p < 0.05). Such findings were observed even when the 10 patients who exhibited ischemia during exercise were excluded (1/3FR: r = 0.34*; PFR: r = 0.37*; TPF: r = -0.36*; *p < 0.05, n = 35). CONCLUSIONS: Our findings suggested that LV diastolic dysfunction, not systolic dysfunction, is associated with limited exercise capacity independent of the occurrence of ischemia.