Silent Myocardial Infarction and Long-Term Risk of Heart Failure: The ARIC Study

Background

Although silent myocardial infarction (SMI) accounts for about one-half of the total number of myocardial infarctions (MIs), the risk of heart failure (HF) among patients with SMI is not well established.

Differential prognostic importance of QRS duration in heart failure and acute myocardial infarction associated with left ventricular dysfunction

BACKGROUND/AIMS: Studies of the prognostic importance of QRS duration in patients with heart failure (HF) have shown conflicting results and few studies have estimated the importance after myocardial infarction (MI). METHODS: The Danish Investigations and Arrhythmia ON Dofetilide (DIAMOND) study randomised 3028 patients to dofetilide (class III antiarrhythmic) or placebo. The study consisted of two almost identical trials conducted simultaneously. One trial included 1518 patients with chronic HF and the other trial 1510 patients with a recent MI. All patients had left ventricular dysfunction. Dofetilide did not influence mortality in either trial. QRS duration was systematically measured at randomisation and was available in 2972 patients. RESULTS: Over a 10 year observation period 1037 (70%) patients in the MI study and 1324 (87%) in the HF study died. In the MI study, risk of death increased 6% for each 10 ms increase in QRS duration (HR=1.06/10 ms increase in QRS (CI=1.04-1.09), p<0.0001) whereas QRS duration had no influence in the HF study after multivariable adjustment. The difference between HF and MI was significant (p<0.0004 for interaction). CONCLUSION: QRS duration predicts death in patients with left ventricular dysfunction who have suffered MI. In patients with HF QRS duration is not predictive of mortality.     

Previously known and newly diagnosed atrial fibrillation: a major risk indicator after a myocardial infarction complicated by heart failure or left ventricular dysfunction

AIMS: To characterize the relationship between known and newly diagnosed atrial fibrillation (AF) and the risk of death and major cardiovascular (CV) events in patients with acute myocardial infarction (MI) complicated by heart failure (HF) and/or left ventricular systolic dysfunction (LVSD). METHODS: The VALIANT trial enrolled 14,703 individuals with acute MI complicated by HF and/or LVSD. AF was assessed at presentation and at randomization (median 4.9 days after symptom onset). Primary outcomes were risk of death and major CV events 3 years following acute MI. RESULTS: A total of 1812 with current AF (AF between presentation and randomization), 339 patients with prior AF (history of AF without current AF), and 12,509 without AF were enrolled. Patients with AF were older; had more prior HF, angina, and MI, and received beta-blockers and thrombolytics less often than those without AF. Three-year mortality estimates were 20% in those without AF, 37% with current AF, and 38% with prior AF. Compared with patients without AF, the multivariable adjusted HR of death was 1.25 (1.03-1.52; p=0.03) for prior AF and 1.32 (1.20-1.45; p<0.0001) for current AF. HR for major CV events was 1.15 (0.98-1.35; p=0.08) and 1.21 (1.12-1.31; p<0.0001). CONCLUSION: AF is associated with greater long-term mortality and adverse CV events with acute MI complicated by HF or LVSD.     

Heart failure after myocardial infarction: clinical presentation and survival

OBJECTIVES: To characterize the presentation and outcome of patients with heart failure (HF) after myocardial infarction (MI) according to left ventricular ejection fraction (LVEF) and test the hypothesis that the outcome of HF did not change over time. BACKGROUND: Little is known about the presentation and outcome of HF post-MI and how these may have changed over time. METHODS: Using the Rochester Epidemiology Project, all residents of Olmsted County, Minnesota who experienced an incident MI between 1979 and 1998 were identified; MI and HF were validated using standardized criteria. Subjects were followed through their community medical record. RESULTS: Between 1979 and 1998, 1915 patients with incident MI and no prior history of HF were identified. Of these, 791(41%) experienced new onset HF as defined by Framingham criteria during 6.6+/-5.0 years of follow-up. Forty-seven percent were men, mean age was 73+/-12 years. Forty-four percent had impaired LVEF, 18% preserved LVEF and 38% had no LVEF measurement within 60 days after the HF event. Median survival after HF onset was 4 years and at 5 years after HF onset, only 45% were alive. Older age, male sex, comorbidity, hypertension and no LVEF assessment were associated with increased risk of death, however, patients with impaired LVEF had the worst outcome. Over time, survival did not improve (HR for year: 1.00; 95% CI 0.99, 1.02; P=0.919) even after adjustment for baseline characteristics. CONCLUSION: In this geographically defined cohort of patients with MI, new onset HF after the MI was frequent. When measured, LVEF was most frequently reduced, consistent with systolic heart failure. Mortality was high and did not decline over time and death was independently associated with male sex, older age, hypertension and comorbidity. It also differed according to LVEF, which was inconsistently ascertained in this setting, potentially representing practice opportunities.     

The impact of morbid events on survival following hospitalization for complicated myocardial infarction

BACKGROUND: Little is known about the importance of morbid events with respect to longer term survival following MI hospital discharge. AIMS: Establish the risk of death associated with morbid events following initial discharge from MI hospitalization. METHODS: We examined the rates of morbid events (reinfarction, stroke/TIA, revascularization, heart failure (HF) hospitalization, cardiovascular hospitalization and all-cause hospitalization) and the relationships of these events to subsequent death in patients who survived the initial hospitalization for MI (n = 5301) in the OPTIMAAL trial. Events were classified as Early (< or = 30 days post discharge) and Late (> 30 days post discharge) for an average of 2.7 years follow-up. RESULTS: Death rates were higher in the Early period (0.20 deaths/patient year) than in the Late period (0.05 deaths/patient year). Once a morbid event, excluding revascularization, occurred, the acute hazard ratios (HR, determined by Cox regression) for death on the day of event were higher than at time periods following the event and were highest for reinfarction and stroke/TIA. The acute HRs for death for all 6 morbid events were especially high for events occurring during the Late period. The highest chronic HR for death was associated with HF and all-cause hospitalizations. By contrast, the chronic HR for death from revascularization in both the Early (HR = 0.3) and Late (HR = 0.4) period indicated reduced risk. CONCLUSIONS: The results document event rates following hospitalization for MI, provide quantification of the associated risk for death, and may be useful in designing clinical trials. The serious morbid events examined may serve as potential surrogate endpoints in long-term studies and identify patients that should be targeted for aggressive management.     

T‐Wave Alternans and Heart Rate Variability: A Comparison in Patients with Myocardial Infarction with or without Diabetes Mellitus

Background : The aim of this study was to investigate the differences in T‐wave alternans (TWA) and heart rate variability (HRV) among patients with myocardial infarction with or without diabetes mellitus and the relationship between TWA and HRV. Methods: The study population included 133 patients: 59 patients with myocardial infarction (MI) (group post‐MI without diabetes); 40 myocardial infarction with diabetes (group post‐MI with diabetes); and 34 controls (group control). Cardiac autonomic neuropathy assessment was made using frequency domain (low‐frequency [LF] power, high‐frequency [HF] power, LF/HF) and time domain (SDNN, standard deviation of the averaged normal sinus RR intervals for all 5‐minute segments [SDANN]) of HRV indexes. Both TWA and HRV were measured on the Holter monitor, and TWA was calculated automatically using the time‐domain modified moving average method. Results: TWA values differed significantly between controls (40 ± 16 μV) and group post‐MI with (62 ± 17 μV, P < 0.05) or without (60 ± 15 μV, P < 0.05) diabetes. In addition, group post‐MI with diabetes had lower standard deviation of all normal sinus RR intervals (SDNN), standard deviation of the averaged normal sinus RR intervals for all 5‐minute segments (SDANN), and HF, indicating depressed vagus nerve activity, and higher LF/HF ratio, indicating elevated sympathetic nerve activity, than controls and group post‐MI without diabetes (P < 0.05). TWA correlated with SDNN and SDANN (r = 0.29, 0.31; P < 0.001). Conclusions: TWA was elevated in patients following myocardial infarction, both in those with or without diabetes. Myocardial infarction patients had a lower time domain, HF, and a higher LF/HF ratio HRV, especially in those with diabetes. The analysis of modified moving agerage (MMA)‐based TWA and HRV can be a useful tool for identifying post–myocardial infarction patients at high risk of arrhythmic events. Ann Noninvasive Electrocardiol 2011;16(3):232–238     

Severity of heart failure, treatments, and outcomes after fibrinolysis in patients with ST-elevation myocardial infarction.

AIMS: To define the clinical characteristics, co-morbidities, treatment, and clinical outcomes of patients with varying degrees of heart failure (HF) complicating ST-elevation myocardial infarction (STEMI), and to identify patients at high risk for HF following fibrinolysis. METHODS AND RESULTS: 15,078 STEMI patients enrolled in a worldwide fibrinolytic trial (InTIME-II) were categorised into one of four hierarchical, mutually exclusive groups of HF: shock (n = 719, 5%); severe HF (n = 1082, 7%); mild HF (n = 1619, 11%); no HF (n = 11,658, 77%). In a multivariable model, anterior MI (OR 1.8, 95% CI [1.6; 1.9]), age > or = 65 (OR 1.8 [1.6; 2.0]), prior HF (OR 3.3 [2.6; 4.2]), and creatinine clearance < 60 mL/min (OR 1.8 [1.6; 2.1]) were the four most powerful correlates of HF. Although 30-day mortality was sixfold higher for patients with HF (18.9% vs. 3.1%, P < 0.0001), these patients were less likely to undergo angiography (30% vs. 40%, P < 0.0001) and revascularisation (19% vs. 25%, P , 0.0001), than patients without HF. Likewise, angiotensin-inhibitors and beta-blockers were not optimally utilised in patients with HF following MI. CONCLUSIONS: During the index admission following fibrinolysis 23% of patients had HF. Despite a higher risk profile, patients with more severe HF were treated less aggressively than patients without HF.     

Predictors of the first heart failure hospitalization in patients who are stable survivors of myocardial infarction complicated by pulmonary congestion and/or left ventricular dysfunction: a VALIANT study.

AIMS: We sought to assess the incidence of and prognostic factors for heart failure (HF) hospitalization among survivors of high-risk acute myocardial infarction (MI). METHODS AND RESULTS: We assessed the risk of an initial hospitalization for HF in 11 040 stable MI patients (no major non-fatal cardiovascular events or deaths within 45 days of randomization) without a prior history of HF enrolled in the VALIANT trial. Multivariable models were developed to identify independent predictors of HF and HF or cardiovascular death. Of 11 040 stable post-MI patients, 1139 (10.3%) developed HF during the median 25-month follow-up at a rate of approximately 3.4% per year. Most patients, 824 (72.3%), did not have a symptomatic recurrent MI between randomization and the onset of HF. The most important predictors of HF were older age, antecedent diabetes, prior MI before index MI, and reduced renal function. HF markedly increased the risk of death [HR(hazard ratio) 8.22; 95% CI(confidence interval), 7.49-9.01]. CONCLUSION: HF post high risk-MI occurs in a time-dependent fashion and is usually not directly related to re-infarction. Patients who experience HF beyond the acute phase have increased mortality. Long-term survivors of high-risk MI should be followed closely and treated aggressively beyond the acute MI period.     

Association of silent myocardial infarction on electrocardiogram and coronary artery calcium: The Multi-Ethnic Study of Atherosclerosis

Background

Silent myocardial infarction (SMI) on electrocardiogram (ECG) is associated with atherosclerotic cardiovascular disease, but the relationship between SMI on ECG and coronary artery calcium (CAC) remains poorly understood.

Objective

Characterize the relationship between SMI on ECG and CAC.

Methods

Eligible participants from the Multi-Ethnic Study of Atherosclerosis study had ECG and CAC scoring at study enrollment (2000–2002). SMI was defined as ECG evidence of myocardial infarction in the absence of a history of clinical cardiovascular disease. CAC was modeled both continuously and categorically. The cross-sectional relationships between SMI on ECG and CAC were assessed using logistic regression and linear regression.

Results

Among 6705 eligible participants, 178 (2.7%) had baseline SMI. Compared to participants without SMI, those with SMI had higher CAC (median [IQR]: 61.2 [0–261.7] vs. 0 [0–81.5]; p < .0001). Participants with SMI were more likely to have non-zero CAC (74% vs. 49%) and were more likely to have CAC ≥ 100 (40% vs. 23%). In a multivariable-adjusted logistic model, SMI was associated with higher odds of non-zero CAC (odds ratio 2.17, 95% CI 1.48–3.20, p < .0001) and 51% higher odds of CAC ≥ 100 (odds ratio 1.51, 95% CI 1.06–2.16, p = .02).

Conclusion

An incidental finding of SMI on ECG may serve to identify patients who have a higher odds of significant CAC and may benefit from additional risk stratification to further refine their cardiovascular risk. Further exploration of the utility of CAC assessment in this patient population is needed.     

Beneficial effects of long-term treatment with enalapril on cardiac function and heart rate variability in patients with old myocardial infarction

BACKGROUND: The beneficial effects of the early use of angiotensin-converting enzyme inhibitors (ACEis) in patients with acute myocardial infarction (MI) are well documented. However, the effects of ACEis in patients with an old MI and preserved cardiac function have not yet been studied. We examined the effects of 12 months of enalapril treatment in patients with previous MI. METHODS AND RESULTS: Thirteen patients with an old MI and no overt congestive heart failure (CHF), aged 70 +/- 2 years, were treated with enalapril for 12 months. We also included 13 age- and sex-matched control patients who had a similar clinical background but were not treated with enalapril. Holter electrocardiography and echocardiography were performed at entry and after 12 months of treatment. Heart rate variability, low- and high-frequency powers (LF and HF), and the ratio between LF and HF (LF/HF) were analyzed. Changes from baseline to 12 months in HF, LF/HF, left ventricular end-diastolic dimension (LVEDD), and end-systolic dimension (LVESD) were significantly different in the enalapril group (HF, 8.1 +/- 0.9 to 9.3 +/- 0.9 milliseconds: LF/HF, 1.65 +/- 0.11 to 1.53 +/- 0.16; LVEDD, 57.2 +/- 1.6 to 54.7 +/- 1.6 mm; LVESD, 40.0 +/- 2.4 to 36.3 +/- 1.9 mm) compared with the control group (HF, 8.9 +/- 0.9 to 8.5 +/- 0.7 milliseconds; LF/HF, 1.78 +/- 0.18 to 1.88 +/- 0.15; LVEDD, 52.3 +/- 2.5 to 55.9 +/- 2.2 mm; LVESD, 32.5 +/- 2.6 to 36.1 +/- 2.6 mm; P < .05). The delta change (delta) in LVESD between the end and the start of study correlated inversely with deltaHF (r = -0.56; P < .05) and positively with deltaLF/HF (r = 0.65; P < .01). CONCLUSION: Our results suggest possible ongoing structural changes in patients with old MI even in the absence of overt CHF. Enalapril seemed to prevent such changes and to restore cardiac autonomic tone toward normal. Further prospective studies using a larger sample size are warranted to confirm potential beneficial effects of ACEis in patients with previous MI and preserved left ventricular function.     

动态心电图在老年无症状性心肌缺血及伴发心律失常检测中的诊断价值

目的评价动态心电图（DCG）对老年冠心病患者无症状性心肌缺血（SMI）及相伴发的心律失常的诊断价值。方法回顾性分析66例临床诊断为冠心病的老年患者DCG监测结果及临床资料,评价SMI发作特点及与年龄的关系;SMI时ST-T改变幅度、持续时间与相关心律失常的关系;受累导联与冠状动脉造影结果相关性分析。结果66例患者中48例出现SMI,共计218阵SMI发作;上午6：00至12：00SMI的发作频率最高有110阵（50．5％）;SMI发作快频率依赖者32例（66．7％）,慢频率依赖者5例（10．4％）;SMI发作伴发心律失常33例,检出率79．6％;随年龄增长SMI发生率增高,年龄65-75岁患者中发生118阵,（4．3±2．9）次,人,年龄75-85岁患者中SMI发作97阵,（5．2±2．9）次／人。结论SMI是老年冠心病常见的表现形式,动态心电图能及早检出SMI的存在及其伴发的心律失常,利于评估猝死风险,具有独特的应用价值。     

Prevalence and prognostic significance of daily-life silent myocardial ischaemia in middle-aged and elderly subjects with no apparent heart disease.

AIMS: We aimed to determine the prevalence and prognostic significance of daily-life silent myocardial ischaemia (SMI) in healthy middle-aged and elderly subjects with no previous heart disease. METHODS AND RESULTS: Six hundred and seventy-eight healthy men and women between 55 and 75 years of age and with no history of cardiovascular disease or stroke were included. Baseline examinations included physical examination, fasting laboratory testing, and 48 h ambulatory electrocardiogram monitoring. An episode of ischaemia was defined by a down-sloped or horizontal ST depression of at least 1 mm at a duration of at least 1 min. Seventy-seven subjects (11.4%) had SMI. All participants were followed for up to 5 years. In 77 subjects with SMI, 16 (20.7%) had an event (death or myocardial infarction). In 601 subjects without SMI, 50 (8.3%) had an event. The hazard ratios for SMI in relation to cardiac and combined events after correction for conventional risk factors were 3.1 [(1.24-7.97), P=0.016] and 1.97 [(1.06-3.69), P=0.033], respectively. CONCLUSION: SMI as detected by Holter monitoring was detected in 11.4% of these subjects and was associated with more than three-fold increase in the cardiac event rate after correction for risk factors, implying that this test could be used to identify high-risk individuals among these subjects.     

The timing of development and subsequent clinical course of heart failure after a myocardial infarction.

AIMS: Myocardial infarction (MI) is a common cause of heart failure (HF), which may develop early and persist or resolve, or develop late. The cumulative incidence, persistence, and resolution of HF after MI are poorly described. The aim of this study is to describe the natural history and prognosis of HF after an MI. METHODS AND RESULTS: Patients with a death or discharge diagnosis of MI in 1998 were identified from records of hospitals providing services to a local community of 600 000 people. Records were scrutinized to identify the development of HF, defined as signs and symptoms consistent with that diagnosis and treated with loop diuretics. HF was considered to have resolved if diuretics could be stopped without recurrent symptoms. Totally, 896 patients were identified of whom 54% had died by December 2005. During the index admission, 199 (22.2%) patients died, many with HF, and a further 182 (20.3%) patients developed HF that persisted until discharge, of whom 121 died subsequent to discharge. Of 74 patients with transient HF that resolved before discharge, 41 had recurrent HF and 38 died during follow-up. After discharge, 145 (33%) patients developed HF for the first time, of whom 76 died during follow-up. Overall, of 281 deaths occurring after discharge, 235 (83.6%) were amongst inpatients who first developed HF. CONCLUSION: The development of HF precedes death in most patients who die in the short- or long-term following an MI. Prevention of HF, predominantly by reducing the extent of myocardial damage and recurrent MI, and subsequent management could have a substantial impact on prognosis.     

Heart failure on admission and the risk of stroke following acute myocardial infarction: the VALIANT registry.

AIMS: We sought to assess the relative contribution of heart failure (HF) on admission for an acute myocardial infarction (MI) to the subsequent in-hospital stroke risk. METHODS AND RESULTS: The VALsartan In Acute myocardial iNfarcTion (VALIANT) registry enrolled 5573 consecutive MI patients at 84 international sites from 1999 to 2001. We calculated odds ratios (ORs) for stroke and adjusted for baseline characteristics, Killip Class, and risk factors for stroke, such as diabetes and prior HF. In-hospital stroke occurred in 81 (1.5%) patients. HF was present on admission in 38% of patients who developed a stroke and in 24% who did not (P=0.001). Older age (OR 1.03 increase/year, 95% confidence interval (CI) 1.01-1.04), Killip Class III (OR 1.66, CI 0.86-3.19) or IV (OR 4.85, CI 1.69-13.93), history of hypertension (OR 1.73, CI 1.06-2.82), and history of stroke (OR 1.89, CI 1.06-3.37) were more common in patients who had in-hospital stroke. In-hospital mortality in patients with and without stroke was 27.2 and 6.5%, respectively (P<0.001). CONCLUSION: Patients with stroke after MI have a dismal prognosis. The presence of HF on admission for an acute MI increases in-hospital stroke risk. HF treatments may modify the risk of stroke.     

The Significance of Heart Rate Turbulence in Predicting Major Cardiovascular Events in Patients after Myocardial Infarction Treated Invasively

Introduction: The role of heart rate turbulence (HRT) related to baroreflex sensitivity in predicting mortality after myocardial infarction (MI) has been confirmed by several investigators. However, the significance of HRT in predicting major adverse cardiovascular events (MACE) following acute MI is unknown. Purpose: To analyze the prognostic value of HRT and other independent risk factors associated with autonomic regulation of MACE. Methods: HRT was assessed based on 24‐hour Holter recordings in 500 patients (pts) with acute MI treated invasively (352 M, aged 60.58 years). Turbulence onset (TO,%), slope (TS, ms/RR interval) and timing (TT) were calculated. TO ≥ 0, TS ≤ 2.5 and TT ≥ 10 were considered abnormal; classic and own categories were defined. Time domain heart rate variability (HRV) parameters were also calculated. Within 30.1 ± 15.1 months of follow‐up, MACE occurred in 116 pts. Results: Abnormal TO, TS, and TT were significantly more frequent in patients with MACE (P < 0.05 for each parameter, classic and own categories). In long‐term follow‐up, the largest differences in MACE were observed in patients with own category comprising abnormal TO, TS, and TT. Combining HRT parameters with SDNN (total HRV index) augmented their predictive value. Independent risk factors for MACE were TT, SDNN and rMSSD (a parasympathetic activity index) (HR 2.44, 1.71 and 1.69 respectively; P < 0.05). Conclusion: Abnormal HRT distinguishes patients at risk of MACE after MI. Own category encompassing three abnormal HRT parameters best differentiates patients at risk of MACE. Turbulence timing is a strong independent risk factor for MACE following MI.     

Myocardial infarction in young adults under 30 years: risk factors and clinical course

The clinical features and course of 30 patients (26 men and 4 women) under 30 years of age (mean age 27.3 years) with an acute myocardial infarction (MI) are described. The most common risk factor among this group of patients was smoking in 20 patients (66%). The prevalence of the other risk factors was low: hyperlipidemia in four patients and family history of ischemic disease in another four patients, diabetes mellitus, hypertension, and obesity each in one patient. Seven patients (23%) had none of the conventional risk factors. Three patients were exerting themselves prior to the onset of their MI pain; all of them had normal coronaries. Five patients experienced chest pain prior to MI, among them only two experienced classical angina pectoris. Eighteen patients underwent uncomplicated MI. The complications in the other 12 during the acute MI were rhythm disturbances in eight and congestive heart failure in four. Cardiac catheterization was performed in 25 patients. The occurrence of zero, one, or multivessel disease was equal. The 30 patients were followed up from six months to 15 years (mean 7 years). In 18 patients circulating aggregated platelets were measured one year after the MI. Elevated values were found in all of them (mean +/- SD 34.9 +/- 9.1%). In 6 of the 18, all heavy smokers, extreme values were found in the range of 39-55%. Three out of the 30 patients died within five years after their first MI. The other 15 patients developed complications, most of them angina pectoris. Five patients were hospitalized for reinfarction. None of the 30 underwent aortocoronary bypass operation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Orthostatic hypotension and the risk of atrial fibrillation and other cardiovascular diseases: An updated meta‐analysis of prospective cohort studies

The relationships between orthostatic hypotension (OH) and some kinds of cardiovascular disease are inconsistent among studies. This updated meta‐analysis was conducted in hopes of producing progress on this topic. A systematic database search was performed in electronic databases, including the Chinese Biomedical Database (CBM), PubMed, Web of Science, and the Cochrane Library. Summary hazard ratio (HR) estimates with 95% confidence intervals (CIs) were calculated by a random‐effects model. Statistical heterogeneity was assessed with Cochran's Q test and the I² statistic. From 1462 potentially eligible records, 15 studies met the inclusion criteria. Subjects with OH had a high risk of heart failure (HF) and atrial fibrillation (AF) (pooled HR 1.34, 95% CI 1.17‐1.52, P < 0.001 and pooled HR 1.51, 95% CI 1.28‐1.79, P < 0.001, respectively). This meta‐analysis also showed significant associations between OH and the risks of developing coronary heart disease (CHD) (pooled HR 1.44, 95% CI 1.18‐1.75, P < 0.001) and myocardial infarction (MI) (pooled HR 1.52, 95% CI 1.12‐2.06, P = 0.008). Our study suggests that OH is positively associated with high risks of HF and AF. Moreover, it may be related to high risks of CHD and MI.     

Tissue kallikrein deficiency aggravates cardiac remodelling and decreases survival after myocardial infarction in mice

BACKGROUND: Tissue kallikrein (TK) is a major kinin-releasing enzyme present in arteries. TK is involved in cardioprotection in the setting of acute myocardial ischaemia but its role in post-ischaemic heart failure (HF), a major cause of delayed mortality after myocardial infarction (MI), is unknown. AIM: To determine whether TK deficiency in the mouse influences survival and cardiac remodelling after MI. METHODS: MI was induced in 10 week-old male TK-deficient mice and wild-type littermates. Survival was assessed up to 14 months. Cardiac morphological and functional parameters were serially measured by echocardiography. In another experiment, myocardial capillary density and NOS content were evaluated at 3 months. RESULTS: Infarct size was similar in both genotypes. MI resulted in severe cardiac dysfunction. Up to 12 months after MI, TK(-/-) mice displayed an increased mortality rate (P<0.05, relative risk of death=3.41) and aggravation of left ventricular hypertrophy and dilatation by comparison with TK(+/+) (+18% and +27% respectively, both P<0.05). NOS1 and NOS3 were abnormally regulated in the heart of TK(-/-) mice after MI. CONCLUSIONS: TK exerts a protective role in HF in mice. Coronary effects are probably involved. As partial genetic deficiency in TK activity occurs in humans, TK-deficient subjects may be at increased risk of mortality in HF.     

Development and course of heart failure after a myocardial infarction in younger and older people

Background Acute myocardial infarction （AMI） is a common cause of heart failure （HF）, which can develop soon after AMI and may persist or resolve or develop late. HF after an MI is a major source of mortality. The cumulative incidence, prevalence and resolution of HF after MI in different age groups are poorly described. This study describes the natural history of HF after AMI according to age. Methods Patients with AMI during 1998 were identified from hospital records. HF was defined as treatment of symptoms and signs of HF with loop diuretics and was considered to have resolved if loop diuretic therapy could be stopped without recurrence of symptoms. Patients were cate- gorised into those aged 〈 65 years, 65-75 years, and 〉 75 years. Results Of 896 patients, 311,297 and 288 were aged 〈 65, 65-75 and 〉75 years and of whom 24%, 57% and 82% had died respectively by December 2005. Of these deaths, 24 （8%）, 68 （23%） and 107 （37%） oc- curred during the index admission, many associated with acute HF. A further 37 （12%）, 63 （21%） and 82 （29%） developed HF that persisted until discharge, of whom 15, 44 and 62 subsequently died. After discharge, 53 （24%）, 55 （40%） and 37 （47%） patients developed I-IF for the first time, of whom 26%, 62% and 76% subsequently died. Death was preceded by the development of HF in 35 （70%）, 93 （91%） and 107 （85%） in aged 〈 65 years, 65-75 years and 〉75 years, respectively. Conclusions The risk of developing HF and of dying after an MI in- creases progressively with age. Regardless of age, most deaths after a MI are preceded by the development of HF.     

Myocardial infarction in thrombotic thrombocytopenic purpura: a single-center experience and literature review

Background: Several case reports and series have described myocardial infarctions (MIs) in patients hospitalized for thrombotic thrombocytopenic purpura (TTP). The exact magnitude and outcome of this complication are unknown. Methods: Electronic medical records for patients admitted to Wake Forest University Baptist Medical Center were examined from 1996 to 2005. Those patients having a diagnosis of TTP during the hospitalization period were included in the analysis. Only patients’ initial episodes of TTP were analyzed. Baseline cardiac and TTP risk factors were documented. Outcomes analyzed included MIs, arrhythmias, development of congestive heart failure and death. Results: Eighty‐five patients diagnosed with TTP were identified with 13 (15.3%) having MIs, as defined by an elevation of cardiac enzymes. Median troponin I value was 5.9 ng/mL (range 3.7–8.8 ng/mL). Twelve patients had non‐ST segment elevation MIs and one had ST segment elevation. Two of 13 patients who had echocardiographic analysis had documented wall motion abnormalities. There was no difference between non‐MI and MI patients in cardiac risk factors, prior cardiac events, history of thromboembolic disease or heart failure. There was no in‐hospital mortality difference. Conclusion: MI is an important complication of TTP, identified in 15.3% of patients in our study. Routine cardiovascular evaluation with cardiac enzymes, electrocardiography, and telemetry is warranted in acute TTP patients. Appropriate intervention is yet to be determined.