The impact of home electrocardiograph measurement rate on the detection of atrial fibrillation recurrence after ablation: A prospective multicenter observational study.

Background: This multicenter prospective observational study examined the impact of additionally using a home electrocardiograph (ECG) to detect atrial fibrillation (AF) recurrence after ablation. Methods: Between May 2019 and December 2020, 128 patients undergoing ablation were enrolled in the study. After performing ablation, they were instructed to measure their ECGs at home using Complete (ECG paired with a blood pressure monitor; Omron Healthcare, Japan) every day and to visit the hospital every 3 months until after 12 months for 24-hour Holter ECG and 12-lead ECG as usual care (UC). Results: After ablation, 94 patients were followed up, and AF recurrence at 12 months was detected more commonly in adjudicators-interpreted Complete (31 [33 %]) than in UC (18 [9 %]) (hazard ratio 1.95, 95 % confidence interval [95 %CI] 1.35-2.81, P < 0.001). In patients with recurrent AF found via both modalities (n = 16), the time to first AF detection by Complete was 40.9 ± 73.9 days faster than that in UC (P = 0.04). Notably, when the adherence to Complete measurement was divided by 80 %, the add-on effect of Complete on the detection of recurrent AF in UC indicated the hazard ratio (HR) of 1.71 (95 %CI 0.92-3.18, P = 0.09) for the low adherence (<80 %) group, but it was significant for the high adherence (≥80 %) group, with HR of 2.19 (95 %CI 1.43-3.36, P < 0.001). Conclusions: Despite a shorter measurement time, Complete detected recurrent AF more frequently and faster compared with UC after AF ablation. A significant adherence-dependent difference of Complete was found in detecting AF recurrence.

Prognostic value of left ventricular mechanical dyssynchrony induced by exercise stress in patients with normal myocardial perfusion single-photon emission computed tomography.

BACKGROUND: Left ventricular mechanical dyssynchrony (LVMD) induced by exercise stress was reported to be clinically useful in detecting multivessel coronary artery diseases. The aim of this study was to compare the prognostic value of LVMD induced by pharmacological stress with that induced by exercise stress. METHODS: We retrospectively examined 918 consecutive patients who underwent exercise (N = 310) or pharmacological stress (N = 608) 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) with normal myocardial perfusion. LVMD was evaluated by phase analysis as the indices of phase bandwidth and phase standard deviation (PSD). RESULTS: During the follow-up period (2.2 ± 1.9 years), 74 major cardiac events (MCEs) occurred (7 cases of cardiac death, 17 cases of heart failure, and 50 cases of coronary intervention). In global patients, the indices of LVMD on rest images were significantly greater in patients with MCEs (bandwidth (°): 51 ± 31 vs 37 ± 21, P = .001, PSD: 14 ± 9 vs 10 ± 6, P = .001). The exercise stress bandwidth was significantly higher in patients with MCEs (62 ± 37° vs 42 ± 21°, P = .026), as was the pharmacological stress bandwidth (57 ± 35° vs 43 ± 24°, P = .006). Multivariate analysis demonstrated the exercise stress bandwidth to be an independent predictor of MCEs (HR 1.017, CI 1.003 to 1.032, P = .019), but the pharmacological stress bandwidth had no influence on MCEs. CONCLUSIONS: LVMD induced by exercise stress was an independent predictor of MCEs in patients with normal perfusion SPECT, whereas that induced by pharmacological stress had no association with further events.

Cardiovascular event risk estimated by myocardial perfusion SPECT combined with clinical data.

Myocardial scintigraphy plays important roles in the diagnosis of coronary artery disease, prognostic risk stratification, and determination of the treatment policy. Recently, several large-scale clinical trials reported that coronary intervention was not necessarily advantageous for preventing future cardiac events in patients with stable angina. This review summarizes how we can estimate cardiac event risks based on Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS), and describes that the combination of scintigraphy and other clinical features leads to more accurate stratification of prognosis and the determination of subsequent treatment policy.

Cardiovascular event risk estimated after coronary revascularization and optimal medical therapy: J-ACCESS4 prognostic study.

BACKGROUND: An assessment of cardiac events and survival using quantitative gated myocardial single-photon emission computed tomography (SPECT) (J-ACCESS) associated several risk factors with cardiac events in Japan. The clinical course after revascularization and/or optimal medical therapy (OMT) was followed in patients with coronary artery disease (CAD) at moderate-to-high risk estimated by software incorporating the J-ACCESS risk model. The present study aimed to determine the relevance of changes in estimated risk to outcomes of these therapies. METHODS: This study included 494 patients with possible or definite CAD who underwent initial pharmacological stress 99mTc-tetrofosmin myocardial perfusion SPECT (MPS) before and eight months after therapy. Major cardiac event risk during 3 years of follow-up was calculated using an equation based on that in the J-ACCESS study. Patients with ≥ 10% cardiac event risk estimated at the first MPS (n = 31) were analyzed and followed up for at least 1 year. RESULTS: Estimated risk was reduced by ≥ 5% in 14 patients (45%) after therapy. During a follow-up period of 22.1 ± 6.7 months, one patient without such reduction had a major cardiac event. Mean %summed stress scores significantly decreased from baseline to follow-up in patients with and without risk reduction. Left ventricular ejection fraction (LVEF [%]) at rest was significantly increased at the second, compared with the first MPS between patients with, than without risk reduction (57 ± 17 vs. 45 ± 16%, p = 0.001 and 50 ± 11 vs. 49 ± 9%, p = 0.953, respectively). CONCLUSIONS: A reduction in cardiac ischemia and an increase in LVEF by revascularization and/or OMT were necessary to avoid cardiac events among patients with moderate-to-high estimated risk, and changes in event risk were quantifiable.

IVUS-Guided Wiring Improves the Clinical Outcomes of Angioplasty for Long Femoropopliteal CTO Compared with the Conventional Intraluminal Approach.

AIMS: This study aimed to assess the clinical efficacy of intravascular ultrasound (IVUS)-guided intraplaque wiring for femoropopliteal (FP) chronic total occlusion (CTO). METHODS: This single-center, retrospective, observational study was performed at the Japanese Red Cross Kyoto Daini Hospital. From March 2013 to June 2017, a total of 75 consecutive patients (mean age: 75.4±8.5 years; 59 males), who underwent endovascular treatment (EVT), having 82 de novo FP-CTO lesions, were enrolled in this study. Eleven of the lesions that met the exclusion criteria were excluded, and the remaining 71 lesions were divided into the IVUS-guided wiring group (n=34) and non-IVUS-guided wiring group (n=37). Primary patency, defined as a peak systolic velocity ratio of ＜2.4 on duplex ultrasonography, and freedom from clinically driven target lesion revascularization (CD-TLR) at 12 months were the primary outcomes. RESULTS: The mean lesion length was 21.6±8.9 cm. The frequencies of primary patency and freedom from CD-TLR were significantly higher in the IVUS-guided wiring group than in the non-IVUS-guided wiring group (70.0% vs. 52.2%, p=0.045; 83.9% vs. 62.8%, p=0.036, respectively). The complete clinically true lumen angioplasty rate was also higher in the IVUS-guided wiring group than in the non-IVUS-guided wiring group (91.1% vs. 51.3%, p＜0.001, respectively). The clinically true and false wire passage rates were respectively 97.3% and 2.7% in the IVUS-guided wiring group. CONCLUSION: IVUS-guided wiring improves the clinical outcomes of EVT for FP-CTO by achieving a high clinically true lumen wire passage rate.

The frequency and clinical characteristics of in-stent restenosis due to calcified nodule development after coronary stent implantation.

The purpose of this study was to evaluated the clinical characteristics of calcified nodule-like in-stent restenosis (ISR) lesions using optical coherence tomography (OCT) in vivo. A total of 124 ISR lesions that were treated with a repeat coronary intervention under OCT guidance were included in this analysis. ISR neointimal morphology was classified as "calcified nodule-like ISR", that appeared as a high-backscattering protruding mass with an irregular surface covered by signal-rich bands, or "non-calcified nodule-like ISR". The maximum arc and thickness of calcium behind the stent struts was also measured. Of the 124 ISR lesions, calcified nodule-like ISR was observed in 11 lesions (9%). OCT analysis data showed that the maximum arc of calcium and the maximum calcium thickness behind the stent were significantly larger in the calcified nodule-like ISR lesions than in the non-calcified nodule-like ISR lesions (269 ± 51 vs. 179 ± 92°, p < 0.01 and 989 ± 174 vs. 684 ± 241 µm, p < 0.01, respectively). The enlargement of the stent area was significantly larger in the calcified nodule-like ISR lesions than in the non-calcified nodule-like ISR lesions (1.6 ± 2.3 vs. 0.7 ± 1.3 mm2, p = 0.02). As a result, the enlargement of the lumen area tended to be larger in the calcified group (2.8 ± 1.7 vs. 2.4 ± 1.3 mm2, p = 0.3). Calcified nodule-like neointima within the stent could develop in approximately 10% of all ISR lesions, especially within stents deployed in severely calcified lesions.

Utility of angiography-physiology coregistration maps during percutaneous coronary intervention in clinical practice.

This study aimed to evaluate the utility and feasibility of physiological maps coregistered with angiograms using the pullback of a pressure guidewire with continuous instantaneous wave-free ratio (iFR) measurements. iFR pullback was obtained for 70 lesions from 70 patients with stable angina pectoris using SyncVision (Philips Corp.). Physiological maps were created, whereby the post-intervention iFR (post-iFR) was predicted as iFRpred. The iFR gap was defined if the difference between the iFRpred and post-iFR was ≥ 0.3. The lesion morphology changed from that during the physiological assessment to that during the angiographic assessment in 26 lesions (37.1%). In particular, 22.6% of angiographic tandem lesions changed to physiological focal lesions. The mean pre-intervention iFR, post-iFR, and iFRpred were 0.73 ± 0.17, 0.90 ± 0.06, and 0.93 ± 0.05, respectively. The mean difference between the iFRpred and post-iFR was 0.029 ± 0.099, with 95% limits of agreement of -0.070-0.128. iFR gaps occurred in 28 patients (40%). Notably, a new iFR gradient causing a ≥ 0.03 iFR drop after stenting occurred in 11 (15.7%) cases. The study patients were divided into two groups according to biases between post-iFR and iFRpred < 0.03 (good concordance group) or ≥ 0.03 (poor concordance group). The pre-intervention heart rate was the only independent predictor of poor concordance (odds ratio, 0.936; 95% confidence interval 0.883-0.992; p = 0.027). Physiological maps under resting conditions may contribute to a reduction in unnecessary stent placements without missing lesions requiring treatment. However, the predictive accuracy of post-iFR performance in the present study was slightly lower than that in the previous reports.

Diagnostic Value of Atrial Fibrillation by Built-in Electrocardiogram Technology in a Blood Pressure Monitor.

Background: Hypertension in patients with atrial fibrillation (AF) is a known independent risk factor for stroke. The Complete blood pressure (BP) monitor (Omron Healthcare, Kyoto, Japan) was developed as the first BP monitor with electrocardiogram (ECG) capability in a single device to simultaneously monitor ECG and BP readings. This study investigated whether the Complete can accurately differentiate sinus rhythm (SR) from AF during BP measurement. Methods and Results: Fifty-six consecutive patients with persistent AF admitted for catheter ablation were enrolled in the study (mean age 65.8 years; 83.9% male). In all patients, 12-lead ECGs and simultaneous Complete recordings were acquired before and after ablation. The Complete interpretations were compared with physician-reviewed ECGs, whereas Complete recordings were reviewed by cardiologists in a blinded manner and compared with ECG interpretations. Sensitivity, specificity, and κ coefficient were also determined. In all, 164 Complete and ECG recordings were simultaneously acquired from the 56 patients. After excluding unclassified recordings, the Complete automated algorithm performed well, with 100% sensitivity, 86% specificity, and a κ coefficient of 0.87 compared with physician-interpreted ECGs. Physician-interpreted Complete recordings performed well, with 99% sensitivity, 85% specificity, and a κ coefficient of 0.85 compared with physician-interpreted ECGs. Conclusions: The Complete, which combines BP and ECG monitoring, can accurately differentiate SR from AF during BP measurement.

Visualization of the improvement of myocardial perfusion after coronary intervention using motorized fractional flow reserve pullback curve.

This study aimed to evaluate the feasibility and utility of using motorized pullback of the pressure guidewire to provide a graphic assessment and prediction of the benefits of coronary intervention. Fractional flow reserve (FFR) measurements were performed with motorized pullback imaging in 20 patients who underwent successful percutaneous coronary intervention (PCI) of the left anterior descending artery. Physiological lesion length (PLL) was calculated using frame counts to determine stent length. FFR area was calculated by integrating the FFR values recorded during pullback tracing (FFRarea). The percentage increase in FFR area (%FFRarea) was defined as the ratio of the difference between the pre- and post-intervention FFRarea to the total frame count. The average FFR values were enhanced following PCI, from 0.64 to 0.82, and the median value of the difference between pre- and post-interventional FFR values (D-FFR) and %FFRarea were 0.13 and 10.6%, respectively. The %FFRarea demonstrated a significant positive correlation with D-FFR (R 2, 0.61; p < 0.01). PLL tended to be longer and the %FFRarea was smaller in lesions with a gradual pressure-drop pattern than those with an abrupt pressure-drop pattern (35.37 vs. 20.40 mm, p = 0.07; 5.78 vs. 16.21%, p < 0.05, respectively). Motorized pullback tracing was able to identify the extent and location of stenosis and help in appropriate stent implantation, in addition to visualizing and quantifying the improvement in FFR following PCI.

Cholesterol crystal depth in coronary atherosclerotic plaques: A novel index of plaque vulnerability using optical frequency domain imaging.

BACKGROUND: The involvement of cholesterol crystals (CCs) in plaque progression and destabilization of atherosclerotic plaques has been recently recognized. This study aimed to evaluate the association between the intraplaque localization of CCs and plaque vulnerability. METHODS: We investigated 55 acute coronary syndrome (ACS) and 80 stable angina pectoris (stable AP) lesions using optical frequency domain imaging (OFDI) prior to percutaneous coronary intervention. The distance between CCs and the luminal surface of coronary plaques was defined as CC depth. RESULTS: Although the incidence of CCs had similar frequencies in the ACS and stable AP groups (95% vs. 89%, p = 0.25), CC depth was significantly less in patients with ACS than in those with stable AP (median [25th to 75th percentile]: 68 µm [58 to 92 µm] vs. 152 µm [115 to 218 µm]; p < 0.001). The incidences of plaque rupture, thrombus, lipid-rich plaques, and thin-cap fibroatheroma were significantly greater in patients with ACS than in those with stable AP (62% vs. 18%, p < 0.001; 67% vs. 16%, p < 0.001; 84% vs. 57%, p < 0.01; and 56% vs. 19%, p < 0.001, respectively). CONCLUSION: OFDI analysis revealed that CCs were found in the more superficial layers within the coronary atherosclerotic plaques in patients with ACS than in those with stable AP, suggesting that CC depth is associated with plaque vulnerability. CC depth, a novel OFDI-derived parameter, could be potentially used as an alternative means of evaluating plaque vulnerability in coronary arteries.

Successful Complete Revascularization With PCI Using Super-Low Volume of Contrast Medium in a Patient With Three-Vessel Disease Including 2 Chronic Total Occlusions With Severe Renal Dysfunction.

The most important factor for preventing contrast-induced nephropathy (CIN) during percutaneous coronary intervention (PCI) in patients with severe renal dysfunction is to minimize the contrast volume. Herein, we report a successful case of complete revascularization after 3 separate PCI procedures using a super-low volume of contrast medium in a patient with 3-vessel disease, including two chronic total occlusions (CTOs). A 70-year-old man having exertional angina despite maximal medical therapy was referred to our hospital. He had severe renal dysfunction (estimated glomerular filtration rate 19 mL/minute/1.73 m2). Coronary angiography, in which a total volume of 15 mL (over 3 injections) of contrast medium was used after hydration with normal saline, demonstrated 2 CTOs in the proximal left circumflex artery (LCX) and the proximal right coronary artery (RCA) as well as focal stenosis in the mid left descending artery (LAD). Because the patient refused coronary artery bypass grafting, we opted for revascularization with PCI, divided into 3 procedures. We made full use of microcatheter tip injection and evaluation with intravascular ultrasound and achieved complete revascularization with a total of 31 mL of contrast medium: 9 mL for RCA, 6 mL for LAD, and 16 mL for LCX, without the occurrence of CIN. Additionally, we present tips for performing PCI using super-low contrast medium.

Usefulness of the novel risk estimation software, Heart Risk View, for the prediction of cardiac events in patients with normal myocardial perfusion SPECT.

BACKGROUND: Myocardial perfusion single-photon emission-computed tomography (SPECT) can predict cardiac events in patients with coronary artery disease with high accuracy; however, pseudo-negative cases sometimes occur. Heart Risk View, which is based on the prospective cohort study (J-ACCESS), is a software for evaluating cardiac event probability. OBJECTIVES: We examined whether Heart Risk View was useful to evaluate the cardiac risk in patients with normal myocardial perfusion SPECT (MPS). METHODS AND RESULTS: We studied 3461 consecutive patients who underwent MPS to detect myocardial ischemia and those who had normal MPS were enrolled in this study (n = 698). We calculated cardiac event probability by Heart Risk View and followed-up for 3.8 ± 2.4 years. The cardiac events were defined as cardiac death, non-fatal myocardial infarction, and heart failure requiring hospitalization. During the follow-up period, 21 patients (3.0 %) had cardiac events. The event probability calculated by Heart Risk View was higher in the event group (5.5 ± 2.6 vs. 2.9 ± 2.6 %, p < 0.001). According to the receiver-operating characteristics curve, the cut-off point of the event probability for predicting cardiac events was 3.4 % (sensitivity 0.76, specificity 0.72, and AUC 0.85). Kaplan-Meier curves revealed that a higher event rate was observed in the high-event probability group by the log-rank test (p < 0.001). CONCLUSION: Although myocardial perfusion SPECT is useful for the prediction of cardiac events, risk estimation by Heart Risk View adds more prognostic information, especially in patients with normal MPS.

Clinical Outcome After Permanent Pacemaker Implantation in Patients With a High Percentage of Ventricular Pacing.

Previous reports have suggested that right ventricular apical pacing may lead to cardiac dysfunction. Septal pacing is thought to be superior to apical pacing in the prevention of cardiac dyssynchrony, however, there have been no reports on the contribution of septal pacing to improving clinical outcome.We retrospectively evaluated factors associated with cardiac events in patients with right ventricular pacing.The study population consisted of 256 consecutive patients newly implanted with permanent pacemakers and followed-up for 29 ± 18 months. Cardiac events, consisting of cardiac death or heart failure requiring hospitalization, occurred in 22 patients. Kaplan-Meier curves revealed that patients with a high percentage of ventricular pacing (> 90%, n = 101, group H) had a higher incidence of cardiac events than patients with a low percentage of ventricular pacing (< 10%, n = 83, group L) (P = 0.002). In group H, multivariate analysis showed that age (HR: 1.174, 95%CI: 1.066-1.291, P = 0.001), ejection fraction (EF) (HR: 0.898, 95%CI: 0.836-0.964, P = 0.003), QRS duration during cardiac pacing (HR: 1.059, 95%CI: 1.017-1.103, P = 0.006), and existing basal cardiac diseases (HR: 13.080, 95%CI: 2.463-69.479, P = 0.003) were significant predictors of cardiac events, although pacing site had no significant association with prognosis (P = 0.56).Higher age, lower EF, longer QRS duration during cardiac pacing, and existing basal cardiac diseases are associated with poor prognosis in patients with a high percentage of ventricular pacing.

Clinical implications of coronary pressure measurement after stent implantation.

This study investigated the effect of fractional flow reserve (FFR) after stent implantation on clinical outcomes. Pressurewire measurements and follow-up data were obtained after stent implantation. Regarding the end point, target lesion revascularization (TLR) occurred in 11 patients (15.9%). Patients with TLR had higher frequencies of multiple stenting (54.5 vs. 19.0%, p = 0.01), lower post-interventional FFRs (0.84 vs. 0.88, p = 0.01), and longer stent lengths (42.20 vs. 27.69 mm, p = 0.01) than patients without TLR. The post-interventional FFR cutoff for TLR was 0.79, although this value had a weak discriminatory ability. However, multivariate analysis did not show any significant independent predictors of TLR (odds ratio 6.33; confidence interval 0.75-53.4, p = 0.09). Post-interventional FFR values were not significantly associated with TLR when a sub-analysis was performed in patients who underwent only drug-eluting stent (DES) implantation. It was difficult to achieve post-interventional FFRs of 0.9 or greater. DES implantation eliminated the effect of post-interventional FFR on TLR. Post-interventional FFR was not able to predict TLR in the present study.

Importance of measuring the fractional flow reserve in patients receiving hemodialysis.

Angiography is not always an accurate indicator of physiologically significant stenosis. We examined the usefulness of functional evaluation of coronary stenosis severity by determining the fractional flow reserve (FFR) using a pressure wire in patients who received hemodialysis with angiographically intermediate lesions. We recruited 44 patients with intermediate lesions; of these, 22 were undergoing hemodialysis while 22 were not. Quantitative coronary angiography (QCA) was performed to measure the minimal lumen diameter (MLD) and calculate the percent diameter stenosis (%DS). The FFR was calculated as the ratio of the coronary pressure at the distal stenotic site to the mean aortic pressure during maximum hyperemia. In each group, we investigated the relationship between the FFR and %DS and FFR and MLD. The patients in the hemodialysis group were significantly younger and had more calcified and type B2/C lesions than those in the non-dialysis group. Although the FFR was correlated with both %DS (r = 0.71, p < 0.01) and MLD (r = 0.58, p < 0.01) in the non-dialysis group, the FFR was not correlated with either MLD or %DS in the hemodialysis group. In the hemodialysis group, there was a discordance between the QCA- and FFR-based assessments of the severity of coronary stenosis. In patients receiving hemodialysis, both anatomical and functional assessments should be conducted to determine the physiological significance of the stenosis accurately.

[Clinical characteristics of patients diagnosed as high cardiac event probability by "Heart Risk View"].

"Heart Risk View" is the software to evaluate the cardiac event probability, and it is based on the results of the prospective cohort study (J-ACCESS). We examined the usefulness of this software. Study population consisted of 83 patients, who were diagnosed that cardiac event probability was over 20% by "Heart Risk View." During the follow-up period (596 +/- 356 days), cardiac event occurred in 23 patients (27.7%), including 7 patients death. No significant differences were observed in the ejection fraction by Quantitative Gated SPECT, total defect score calculated from SPECT, and the percentage of stress perfusion abnormality detected by SPECT between event and non-event groups. However, the percentage of cardiac revascularization therapy based on the SPECT was significantly lower in the event group (9 vs. 38%, p = 0.03). In conclusion, cardiac event probability calculated by "Heart Risk View" was reliable in our study cohort. Cardiac event strongly depended on the cardiac ischemia, for which the therapy was difficult because of lesion complexity or combined diseases.

Chronotropic incompetence and autonomic dysfunction in patients without structural heart disease.

AIMS: An attenuated heart rate response to exercise, termed chronotropic incompetence (CI), has been reported to be an independent predictor of cardiovascular mortality. We examined the change in autonomic function during exercise testing and correlated the results with CI. METHODS AND RESULTS: Exercise testing using a bicycle ergometer was performed in 172 patients who had no evidence of cardiac disease. Chronotropic incompetence was defined as the failure to achieve 85% of the age-predicted maximum heart rate, heart rate reserve <80%, or chronotropic response index <0.80. We analysed the relationship between CI and the change in two components of heart rate variability during exercise testing: high-frequency (HF) component (0.15-0.40 Hz) as an index of vagal modulation and the ratio of low-frequency (LF) component (0.04-0.15 Hz) to HF component as an index of sympathovagal balance. Heart rate variability indexes before exercise were similar in patients with and without CI. Percentage changes after exercise in the ratio of LF to HF component were higher in patients with CI than in those without CI (84 +/- 15 vs. 41 +/- 16%, P < 0.05), whereas percentage changes in an HF component were similar in the two groups. CONCLUSION: Our data suggested that CI in patients without structural heart disease was mainly caused by a pathophysiological condition in which sympathetic activation was not well translated into heart rate increase. Further study is needed to determine the post-synaptic sensitivity of the beta-adrenergic receptor pathway in relation to CI.

A case report: 201Tl/99mTc-Pyrophosphate dual-isotope myocardial SPECT for detecting annular subendocardial infarction induced by a transient shock.

The patient was a 74-year-old woman with angina pectoris, who had undergone percutaneous coronary intervention with stent placement in the right coronary artery on October 2, 2007. On November 12 of the same year, she suffered from paroxysmal atrial fibrillation. She was treated with pilsicainide hydrochloride administered by intravenous injection, which was followed by a sudden sinus standstill, with marked bradycardia and a shock state. The patient was then treated with a catecholamine, however, the shock state persisted for about an hour. An electrocardiogram revealed persistent ST depression in leads V4-6 along with elevation of the serum creatinine kinase. A coronary angiography performed on the admission day revealed no abnormality. On the third hospital day, a dual-isotope myocardial SPECT using 201Tl and 99mTc-pyrophosphate demonstrated an annular accumulation of 99mTc-pyrophosphate concordant with the endocardium from apex to the mid-portion of the left ventricle, suggestive of subendocardial infarction. The case is reported here, as there are few reports of subendocardial infarction developing due to ischemia arising from a shock state.

Enhanced activity of ventricular Na+-HCO3- cotransport in pressure overload hypertrophy.

The Na(+)-HCO(3)(-) cotransporter (NBC) plays a key role in intracellular pH (pH(i)) regulation in normal ventricular muscle. However, the state of NBC in nonischemic hypertrophied hearts is unresolved. In this study, we examined functional and molecular properties of NBC in adult rat ventricular myocytes. The cells were enzymatically isolated from both normal and hypertrophied hearts. Ventricular hypertrophy was induced by pressure overload created by suprarenal abdominal aortic constriction of 50% for 7 wk. pH(i) was measured in single cells using the fluorescent pH indicator 2',7'-bis(2-carboxyethyl)5-(6)carboxyfluorescein. Real-time PCR analysis was used to quantitatively assess expression of NBC-encoding mRNA, including SLC4A4 (encoding electrogenic NBC, NBCe1) and SLC4A7 (electroneutral NBC, NBCn1). Our results demonstrate that: 1) mRNA levels of both the electrogenic NBCe1 (SLC4A4) and electroneutral NBCn1 (SLC4A7) forms of NBC were increased by aortic constriction, 2) the onset of NBC upregulation occurred within 3 days after constriction, 3) normal and hypertrophied ventricles displayed regional differences in NBC expression, 4) acid extrusion via NBC (J(NBC)) was increased significantly in hypertrophied myocytes, 5) although acid extrusion via Na(+)/H(+) exchange was also increased in hypertrophied myocytes, the relative enhancement of J(NBC) was larger, 6) membrane depolarization markedly increased J(NBC) in hypertrophied myocytes, and 7) losartan, an ANG II AT(1) receptor antagonist, significantly attenuated the upregulation of both NBCs induced by 3 wk of aortic constriction. Enhanced NBC activity during hypertrophic development provides a mechanism for intracellular Na(+) overload, which may render the ventricles more vulnerable to Ca(2+) overload during ischemia-reperfusion.