Mats Frick

Myocardial infarction with normal coronary arteries is common and associated with normal findings on cardiovascular magnetic resonance imaging: results from the Stockholm Myocardial Infarction with Normal Coronaries study

Myocardial infarction with angiographically normal coronary arteries (MINCA) is an important subtype of myocardial infarction; however, the prevalence, underlying pathophysiology, prognosis and optimal management of this condition are still largely unknown. Cardiovascular magnetic resonance (CMR) imaging has the potential to clarify the underlying pathology in patients with MINCA. The objective of this study was to investigate the diagnostic value of CMR imaging in this group of patients.

Oxygen Therapy in Suspected Acute Myocardial Infarction

BACKGROUND The clinical effect of routine oxygen therapy in patients with suspected acute myocardial infarction who do not have hypoxemia at baseline is uncertain. METHODS In this registry‐based randomized clinical trial, we used nationwide Swedish registries for patient enrollment and data collection. Patients with suspected myocardial infarction and an oxygen saturation of 90% or higher were randomly assigned to receive either supplemental oxygen (6 liters per minute for 6 to 12 hours, delivered through an open face mask) or ambient air. RESULTS A total of 6629 patients were enrolled. The median duration of oxygen therapy was 11.6 hours, and the median oxygen saturation at the end of the treatment period was 99% among patients assigned to oxygen and 97% among patients assigned to ambient air. Hypoxemia developed in 62 patients (1.9%) in the oxygen group, as compared with 254 patients (7.7%) in the ambient‐air group. The median of the highest troponin level during hospitalization was 946.5 ng per liter in the oxygen group and 983.0 ng per liter in the ambient‐air group. The primary end point of death from any cause within 1 year after randomization occurred in 5.0% of patients (166 of 3311) assigned to oxygen and in 5.1% of patients (168 of 3318) assigned to ambient air (hazard ratio, 0.97; 95% confidence interval [CI], 0.79 to 1.21; P=0.80). Rehospitalization with myocardial infarction within 1 year occurred in 126 patients (3.8%) assigned to oxygen and in 111 patients (3.3%) assigned to ambient air (hazard ratio, 1.13; 95% CI, 0.88 to 1.46; P=0.33). The results were consistent across all predefined subgroups. CONCLUSIONS Routine use of supplemental oxygen in patients with suspected myocardial infarction who did not have hypoxemia was not found to reduce 1‐year all‐cause mortality. (Funded by the Swedish Heart–Lung Foundation and others; DETO2X‐AMI ClinicalTrials.gov number, NCT01787110.)

Asymptomatic versus symptomatic persistent atrial fibrillation: clinical and noninvasive characteristics

Abstract. Frykman V, Frick M, Jensen‐Urstad M, Östergren J, Rosenqvist M (South Hospital and Karolinska Hospital, Karolinska Institute, Stockholm, Sweden). Asymptomatic versus symptomatic persistent atrial fibrillation: clinical and noninvasive characteristics. J Intern Med 2001; 250: 390–397.

Effect of intravenous magnesium on heart rate and heart rate variability in patients with chronic atrial fibrillation

The present double-blind, placebo-controlled study investigated the effects of intravenous magnesium on heart rate and rate variability in 30 patients with chronic atrial fibrillation. During standardized conditions, intraindividual variation in heart rate and rate variability was low in patients with chronic atrial fibrillation and magnesium had no effect on heart rate or rate variability.

Myocardial infarction with angiographically normal coronary arteries

Myocardial Infarction with Normal Coronary Arteries (MINCA) is an important subgroup of myocardial infarction with a frequency of at least 3-4% of all myocardial infarctions. The interest and awareness of MINCA have increased recently due to the frequent use of coronary angiography, the description of Takotsubo stress cardiomyopathy and new sensitive troponin assays. Since myocarditis may mimic myocardial infarction it is essential to exclude this in patients with myocardial infarction with angiographically normal coronary arteries. Cardiac magnetic resonance imaging is a cornerstone not only to establish the diagnosis but also an important tool in the search for different causes of myocardial damage. In the future, atherosclerotic burden, hemostatic function, characterization of stressors and inflammation will be important targets for research in this group of patients.

Perceived heart rhythm in relation to ECG findings after direct current cardioversion of atrial fibrillation

Objective: To investigate the agreement between perceived heart rhythm and the ECG-registered heart rhythm, as well as between symptoms and the ECG after direct current (DC) cardioversion of atrial fibrillation (AF). Methods: Consecutive patients with symptomatic AF subjected to DC cardioversion were interviewed about perceived heart rhythm and symptoms one week after restoration of sinus rhythm (SR). An ECG was obtained after the interview. A chance-corrected measure of agreement was calculated by using Cohen’s κ test. Results: 356 patients were enrolled. One week after successful cardioversion 160 patients considered their rhythm to be regular and 222 ECGs showed SR. 130 patients considered their heart rhythm to be regular in agreement with ECG in SR (κ  =  0.34, 95% confidence interval (CI) 0.24 to 0.44), indicating a fair agreement. At the same time 59 patients perceived AF and 134 ECGs showed AF. Thirty eight patients perceived AF, in agreement with AF found on their ECG (κ  =  0.13, 95% CI 0.02 to 0.25), a poor agreement. 141 of 356 patients reported improvement of symptoms in agreement with SR on their ECG (κ  =  0.26, 95% CI 0.15 to 0.36), indicating fair agreement. Perceived SR and improvement of symptoms were strongly associated (n  =  129; p < 0.001). Conclusion: Agreement between perceived heart rhythm and ECG, as well as between improvement of symptoms and SR recorded on the ECG, is no more than poor to fair after successful cardioversion of patients with persistent AF. The association between perceived SR and improvement of symptoms is strong. These findings support the need for objective criteria to select patients who would benefit most from rhythm control. They also support the need for further studies on quality of life of patients with AF, with due attention paid to patients’ perception of their cardiac rhythm.

Cardioversion of atrial fibrillation and its effect on right ventricular function as assessed by tricuspid annular motion

In patients with atrial fibrillation, the reduced right ventricular function determined by tricuspid annular motion before cardioversion returns to normal 1 month after successful cardioversion to sinus rhythm. The simplicity of recording the tricuspid annular motion provides an easy opportunity to assess right ventricular function following electroconversion of atrial fibrillation to sinus rhythm.

Risk factors for myocardial infarction with normal coronary arteries and myocarditis compared with myocardial infarction with coronary artery stenosis.

The interest and awareness of myocardial infarction with normal coronary arteries (MINCA) have increased recently due to the frequent use of coronary angiography, the description of Takotsubo stress cardiomyopathy, and new sensitive troponin analyses. The prevalence of MINCA in all patients with myocardial infarction (MI) was registered during a 3-month period in the Stockholm metropolitan area in Sweden. The results showed that MINCA is more common than previously thought (7%) and affecting one third of every woman with MI. Patients with myocarditis were younger and more often presented with signs of inflammation such as elevated C-reactive protein and fever. Myocarditis constitutes an important differential diagnosis for coronary artery disease. There is a need for larger studies of MINCA, including investigation with cardiac magnetic resonance imaging, to establish prevalence and pathological process in this important subgroup of MI.

Risk Factors and Markers for Acute Myocardial Infarction With Angiographically Normal Coronary Arteries.

Myocardial Infarction with normal coronary arteries (MINCA) is common with a prevalence of 1% to 12% of all myocardial infarctions. The pathogenic mechanisms of MINCA are still unknown, but endothelial dysfunction has been suggested as a possible cause. To investigate risk factors and markers for MINCA, we conducted a case-control study. Considering the reported low prevalence of classical risk factors for coronary heart disease (CHD) in some but not all studies, our hypothesis was that endothelial function and intima-media thickness (IMT) were better, respectively lower, than CHD controls. One hundred patients with MINCA fulfilling diagnostic criteria according to the European Society of Cardiology/American Collage of Cardiology/American Heart Association universal definition of myocardial infarction with myocarditis excluded by cardiac magnetic resonance imaging were investigated. Risk factors, endothelial function (EndoPAT), and IMT were compared to gender- and age-matched patients with myocardial infarction and CHD, respectively healthy controls. Smoking, hypertension, impaired glucose tolerance and diabetes mellitus, inflammatory disease, and psychiatric disorders were more common in patients with MINCA than in healthy controls. In contrast to patients with CHD, the lipid profile was antiatherogenic with low low-density lipoprotein and high high-density lipoprotein cholesterol. There were no major differences between the groups regarding endothelial function and IMT that were in the normal range. In conclusion, the present study showed that MINCA was associated with many established cardiovascular risk factors without major differences in atherosclerosis markers. MINCA patients recalled a high prevalence of emotional stress before admission that together with previous psychiatric vulnerability and female gender speaks strongly in favor of Takotsubo syndrome being an important cause of MINCA.

Early low-dose dobutamine echocardiography predicts late functional recovery after thrombolyzed acute myocardial infarction ☆ ☆☆

BACKGROUND This study was undertaken to evaluate the ability of predischarge low-dose dobutamine echocardiography to predict late left ventricular functional recovery after thrombolyzed acute myocardial infarction. METHODS AND RESULTS Low-dose dobutamine echocardiography was performed in 54 patients 4 +/- 2 days after acute myocardial infarction treated with thrombolysis. Follow-up resting echocardiography was carried out in 49 of these patients at a mean of 18 +/- 6 months later. Viability was defined as recovery of myocardial function at follow-up, expressed as an improvement of wall motion of at least 1 grade or more in at least 2 contiguous infarct zone segments. In 24 of the 49 patients (group I), wall motion at follow-up improved in comparison with the early resting echocardiographic study (1.72 +/- 0.29 vs 1.37 +/- 0.34, P <.001). In the remaining 25 patients (group II), no wall motion enhancement was seen at follow-up (1.57 +/- 0.38 vs 1.58 +/- 0.36, NS). In 22 of the 24 patients in group I, early low-dose dobutamine echocardiography showed improvement in the wall motion score index compared with baseline resting measurements (1.72 +/- 0.29 vs 1.44 +/- 0.24, P <.001). The positive and negative predictive value of early low-dose dobutamine echocardiography to predict functional recovery was 76% and 92%, respectively. CONCLUSION Predischarge low-dose dobutamine echocardiography is an accurate tool for detecting viable myocardium and predicting late left ventricular recovery after acute myocardial infarction treated with thrombolysis.