Cold Spells and the Onset of Acute Myocardial Infarction: A Nationwide Case-Crossover Study in 323 Chinese Cities.

BACKGROUND: Few studies have explored the relationships between cold spells and acute myocardial infarction (AMI) using the information of symptom onset. OBJECTIVES: We assessed the impact of cold spells on AMI onset and the potential effect modifiers. METHODS: We conducted a time-stratified case-crossover study among 456,051 eligible patients with AMI from 2,054 hospitals in 323 Chinese cities between January 2015 and June 2021 during cold seasons (November to March). Nine definitions of cold spells were used by combining three relative temperature thresholds (i.e., lower than the 7.5th, 5th, and 2.5th percentiles) and three durations of at least 2-4 consecutive d. Conditional logistic regressions with distributed lag models were applied to evaluate the cumulated effects of cold spells on AMI onset over lags 0-6 d, after adjusting for daily mean temperature. RESULTS: The associations generally appeared on lag 1 d, peaked on lag 3 d, and became nonsignificant approximately on lag 5 d. Cold spells defined by more stringent thresholds of temperature were associated with higher risks of AMI onset. For cold spell days defined by a daily mean temperature of ≤7.5th percentile and durations of ≥2d, ≥3d, and ≥4d, the percentage changes in AMI risk were 4.24% [95% confidence interval (CI): 2.31%, 6.20%], 3.48% (95% CI: 1.62%, 5.38%), and 2.82% (95% CI: 0.98%, 4.70%), respectively. Significant AMI risks associated with cold spells were observed among cases from regions without centralized heating, whereas null or much weaker risks were found among those from regions with centralized heating. Patients ≥65 years of age were more susceptible to cold spells. DISCUSSION: This national case-crossover study presents compelling evidence that cold spells could significantly increase the risk of AMI onset. https://doi.org/10.1289/EHP11841.

Management and Outcomes of Patients With STEMI During the COVID-19 Pandemic in China.

BACKGROUND: ST-segment elevation myocardial infarction (STEMI) is a fatal cardiovascular emergency requiring rapid reperfusion treatment. During the coronavirus disease-2019 (COVID-19) pandemic, medical professionals need to strike a balance between providing timely treatment for STEMI patients and implementing infection control procedures to prevent nosocomial spread of COVID-19 among health care workers and other vulnerable cardiovascular patients. OBJECTIVES: This study evaluates the impact of the COVID-19 outbreak and China Chest Pain Center's modified STEMI protocol on the treatment and prognosis of STEMI patients in China. METHODS: Based on the data of 28,189 STEMI patients admitted to 1,372 Chest Pain Centers in China between December 27, 2019 and February 20, 2020, the study analyzed how the COVID-19 outbreak and China Chest Pain Center's modified STEMI protocol influenced the number of admitted STEMI cases, reperfusion strategy, key treatment time points, and in-hospital mortality and heart failure for STEMI patients. RESULTS: The COVID-19 outbreak reduced the number of STEMI cases reported to China Chest Pain Centers. Consistent with China Chest Pain Center's modified STEMI protocol, the percentage of patients undergoing primary percutaneous coronary intervention declined while the percentage of patients undergoing thrombolysis increased. With an average delay of approximately 20 min for reperfusion therapy, the rate of in-hospital mortality and in-hospital heart failure increased during the outbreak, but the rate of in-hospital hemorrhage remained stable. CONCLUSIONS: There were reductions in STEMI patients' access to care, delays in treatment timelines, changes in reperfusion strategies, and an increase of in-hospital mortality and heart failure during the COVID-19 pandemic in China.

[Impacts of establishment of chest pain center on the door-to-balloon time and the short-term outcome after primary percutaneous coronary intervention of patients with ST segment elevated myocardial infarction].

OBJECTIVE: To investigate the impact of the establishment of chest pain center (CPC) model based on the pre-hospital real-time tele-12-lead electrocardiogram on the door-to-balloon (D-to-B) time and short-term outcome after primary percutaneous coronary intervention (PPCI) of patients with ST-segment elevated myocardial infarction (STEMI). METHODS: A regular CPC was established with pre-hospital transmitted real-time 12-lead electrocardiogram system for pre-hospital diagnosis of STEMI and enabled the STEMI patients to bypass the emergency room and directly treated in the catheter lab to shorten the D-to-B time. The mean D-to-B time, the short-term outcome and medical costs were compared in PPCI patients before (93 cases, group A) and after (149 cases, group B) the establishment of CPC. RESULTS: After the establishment of CPC, the annual mean D-to-B time was significantly shortened [(127 ± 79) min in group A vs.(72 ± 23 )min in group B, P < 0.01], the shortest monthly mean D-to-B time was remarkably reduced in group B than in group A [(56 ± 11) min vs. (73 ± 14) min, P < 0.01]. The annual ratio of D-to-B below 90 minutes was significantly increased from 62.4% (58/93) in group A to 91.9% (137/149) in group B (P < 0.05) . The in-hospital mortality rate tended to be lower and the incidence of heart failure during hospitalization was significantly reduced in group B compared with group A [3.4% (5/149) vs. 6.5% (6/93), P > 0.05; 14.1% (21/149) vs. 24.7% (23/93), P < 0.05]. The length of hospital stay was slightly shortened from (8.98 ± 4.89) days to (7.79 ± 5.43) days (P > 0.05). Corrected mean medical cost went down by 9.4% (P < 0.05). CONCLUSION: The establishment of CPC may significantly shorten the D-to-B time, improve the short-term outcome and reduce the hospitalization cost for PPCI patients with STEMI.

Comparison of angiographic and IVUS follow-up between the two different drug-eluting stents implanted simultaneously in the same individuals.

BACKGROUND: While, theoretically, a drug-eluting stent (DES) with a biodegradable polymer should reduce the incidence of late in-stent thrombosis, this has not been experimentally tested. OBJECTIVES: This study compared long-term manifestations of the Excel DES, with a biodegradable polymer, to the Endeavor DES, with a biocompatible polymer, in the same individuals. METHODS: Forty-eight patients underwent simultaneous implantation of 1 or more Endeavor stents and 1 or more Excel stents, during the same procedure, and were evaluated with coronary angiography and intravascular ultrasound (IVUS) at least 1 year postprocedure. Within-patient comparisons were made between the Excel- and Endeavor-stented segments for efficacy and safety. RESULTS: A total of 131 stents (69 Endeavor stents and 62 Excel stents) were implanted in 98 lesions among 48 patients. Baseline characteristics of the lesions in the two stented segments groups were comparable. Average follow-up duration was 14.3 ± 2.5 months. In-stent late luminal loss and luminal stenosis were higher in Endeavor-stented segments than in Excel-stented segments (P<.01). The binary restenosis rate was slightly higher in Endeavor-stented segments (4.3% vs. 1.6%; P=.379). In-stent thrombosis, late incomplete stent apposition, and uncovered stent struts were higher in Excel-stented segments than in Endeavor-stented segments (P<.01). There was 1 case of an in-stent coronary aneurysm with an Excel-stented segment. Four segments, in 4 cases (2 in each stent group), required target lesion revascularization. CONCLUSION: This study suggested that, compared to DESs with a biocompatible polymer, DESs with biodegradable polymer do not appear to present an advantage for long-term safety.

[The clinical application of the emergency remedial transthoracic cardiac pacing used by a steel wire loop electrode].

OBJECTIVE: To explore an effective method of emergency remedial cardiac pacing and evaluate its clinical application. METHODS: The transthoracic cardiac pacing was used by a steel wire loop electrode to 18 patients with cardiac arrest or serious bradycardia, after a routine cardiac pacing was failed by way of jugular or subclavian vein. RESULTS: It is a simple procedure used by steel wire loop. All the pacing had been successfully captured the hearts except 5 cases without capturing. There were 3 cases of cardiac arrest, 2 cases of cardiac arrest after electric defibrillation, 1 case of cardiac arrest after electric shock because of ventricular running and all the 5 cases of severe cardiac bradycardia due to serious atrioventricular block caused by high blood potassium were survived. Eight cases of cardiac arrest were successful capture, that was due to the short period of time from cardiac arrest to ventricle puncture than that of 5 cases of ventricular pacing which was not successful [(17.6+/-4.6) minutes vs. (26.4+/-5.4) minutes, P<0.05]. CONCLUSION: The steel wire loop electrode is a safe and reliable emergency cardiac pacing method, which contribute to the rapid establishment of an effective emergency cardiac pacing. When the conventional intravenous cardiac pacing was not successful, the method of emergency transthoracic cardiac pacing used by steel wire loop electrode should be bold and use to improve the successful rate of resuscitation.

[Clinical features of idiopathic ventricular tachycardia of various types and their radiofrequency ablation therapy].

OBJECTIVE: To analyze the clinical features idiopathic ventricular tachycardia (IVT) and evaluate the effect of radiofrequency ablation therapy for their management. METHODS: An retrospective analysis was conducted in 165 IVT patients who received radiofrequency ablation therapy. IVT was classified into 3 types according to the site of origin, namely the right ventricular outflow tract (RVOT-IVT, 86 cases), left ventricular septum (LV-IVT, 75 cases), and left Valsalva sinus (4 cases). RESULTS AND CONCLUSION: RVOT-IVT was more frequent in female patients than in male patients (60 vs 26, M/F ratio of 0.43). In LV-IVT, male patients prevailed (54 vs 21, M/F ratio of 2.57), suggesting a gender difference in the incidence of IVT. IVT occurred mainly in young and middle-age patients. Most RVOT-IVT occurred in the third to fourth decade of life (mean 36-/+12 years), and LV-IVT occurred at a younger age than did RVOT-IVT (mean 26-/+15 years, P<0.01). Twelve-lead ECGs revealed left bundle branch block morphology in RVOT-IVT, and most of them presented with frequent premature ventricular contraction and/or non-sustained ventricular tachycardia. All the RVOT-IVT patients were successfully ablated by radiofrequency energy in pace mapping. LV-IVT patients with right bundle branch block morphology presented sustained ventricular tachycardia for most of the time, and 97% of the patients were successfully managed with radiofrequency ablation in activation mapping. Four IVT patients were characterized by atypical bundle branch block, an inferior axis, and an R/S ratio >1 in lead V3 or V2, and their tachycardia was ablated successfully in the left sinus of Valsalva using pace mapping. Radiofrequency ablation is currently an effective procedure for IVT management.

[Fever and Brugada syndrome: report of 21 cases].

A retrospective analysis of 21 cases of Brugada syndrome treated between 1997 and 2004 was conducted to examine the clinical characteristics of these patients and the relations between fever and Brugada syndrome. Of the 21 patients including one female patient, 4 male patents with Brugada syndrome were confirmed to develop ventricular arrhythmias due to febrile disease, suggesting that fever, one of the common causes for triggering cardiac events in Brugada syndrome, should receive due attention in clinical practice.

[PCR-based site-directed mutagenesis and recombinant expression plasmid construction of a SCN5A mutation (K317N) identified in a Chinese family with Brugada syndrome].

OBJECTIVE: To perform PCR-based site-directed mutagenesis of a new SCN5A mutation (K317N) identified in a Chinese family with Brugada syndrome and construct the recombinant expression plasmid pRc/CMV-Hh1 containing the human cardiac sodium channel alpha subunit (hH1), mutant cDNA. METHODS: A pair of primers was designed according to the restricted sites Sse 8387I and Age I of the SCN5A sequence with the mismatches introduced into primers. Mutagenesis was performed in a single-step PCR, and the fragments amplified by PCR containing the mutation site were subcloned into the pRc/CMV-hH1 vector. RESULTS: Sequence analysis confirmed the presence of the desired mutation site, and a mutation from K (Lys) to N (Asn) in codon 317 was identified in the SCN5A gene, indicating the successful induction of the mutation at K317N of the SCN5A gene. CONCLUSION: PCR site-directed mutagenesis is accurate and highly efficient, and the successfully constructed recombinant expression plasmid pRc/CMV-hH1 (K317N) may provide a molecular basis for further functional and genomic investigation of SCN5A.

Dynamic changes in type I collagen, MMP-1 and TIMP-1 after angioplasty.

OBJECTIVE: To investigate the dynamic changes of type I collagen, and the activity of metalloproteinases-1 (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) after angioplasty. METHODS: The restenotic model of iliac arteries of domestic microswine was established with hypercholesterol feed plus two angioplasties. Angioplastied vessels were harvested at the end of 1, 2, 3 and 6 months after the second angioplasty. Immunohistochemistry, transmission electronic microscopy and image quantitative analysis techniques were employed to study neointimal proliferation, the phenotype of vascular smooth muscle cells (VSMC) and the expression of type I collagen, MMP-1 and TIMP-1. RESULTS: The peak of vascular neointimal proliferation was at 3 months after angioplasty. The expression of type I collagen gradually increased from 1 to 6 months after angioplasty. For MMP-1, expression was lower in the early stage after angioplasty but increase to normal levels of control vessels at 6 months after angioplasty. Expression of TIMP-1 rapidly increased in the early phase after angioplasty, reached peak at 3 months and maintained the high level till 6 months after angioplasty. Meanwhile, the VSMC was predominantly the synthetic phenotype at the early stage and was transformed to the contractive phenotype at the late stage after angioplasty. The ratio of TIMP-1 and MMP-1 was positively related to the area of the neointima and the expression of type I collagen respectively (P < 0.01). CONCLUSION: Type I collagen increased gradually after angioplasty, which might be determined by the ratio of TIMP-1/MMP-1 and also related to the phenotype of VSMC.