Triggering of Acute Coronary Occlusion by Episodes of Vigorous Physical Exertion.

BACKGROUND: There is increasing recognition that heavy exertion can occasionally trigger an acute myocardial infarction (MI), although some uncertainties exist regarding the link. The primary aim of this study was to compare the relative risk (RR) of MI following vigorous exertion between those with confirmed coronary occlusion and those with a non-occluded culprit artery on acute angiography. Secondary aims were to determine if the risk of coronary occlusion is modified by the type of exercise (dynamic or isometric resistance), the frequency of regular exertion or whether the exertion was emotionally charged. METHODS: Seven hundred sixty-two (762) participants with MI (410 with coronary occlusion TIMI 0,1), and 352 (46%) with a non-occluded culprit artery (TIMI 2,3) completed a questionnaire within 4days of admission, detailing episodes of physical exertion in the 28hours prior to symptom onset and the usual frequency of such exertion. Exertion exposures within 1hour prior to symptom onset were compared to subjects' usual yearly exposure, with case-crossover methodology. RESULTS: The RR of symptom onset following heavy physical exertion level ≥6 (exertion scale 1-8), was higher in those with TIMI 0,1 compared to those with TIMI 2,3 flow (RR 6.30, 95% CI 4.70-8.50 vs 3.93, 2.89-5.30). The increased risk of coronary occlusion following vigorous exertion was observed following both dynamic exertion and isometric resistance, and did not differ between exertion types. The highest risk of coronary occlusion following exertion was observed in those who were sedentary (regular vigorous exertion <1day weekly) (RR=77, 95% CI 46-132), whereas in those who frequently perform regular vigorous physical exertion (>4days weekly), the RR of symptom onset during exertion was significantly lower, RR 2.3 (95% CI 1.5-3.6). There was no significant difference in relative risk based on whether the exertion was reported as emotionally charged. CONCLUSIONS: The relative risk that heavy exertion will trigger a non-fatal MI with an occluded artery is greater than for a non-occluded culprit artery. Both dynamic and isometric exertion increase the relative risk of event, while exposure to regular vigorous exertion reduces the relative risk.

Routine aspiration thrombectomy improves the diagnosis and management of embolic myocardial infarction.

OBJECTIVES: Assess the effect of aspiration thrombectomy on diagnosis and management of embolic acute myocardial infarction. BACKGROUND: Discrimination of embolic acute myocardial infarction from atherosclerotic plaque rupture/erosion prompts oral anticoagulation treatment of source of embolus, as well as avoiding unnecessary stenting and dual antiplatelet therapy. However, detection is difficult without aspiration. METHODS: We compared rates of diagnosis of embolic infarction for 2.5 years prior to (pre-RAT) and 2.5 years post routine aspiration thrombectomy (post-RAT). Baseline demographics, outcomes, and treatment strategies were also compared between the embolic infarction and atherosclerotic infarction. RESULTS: Diagnosed embolic infarction rose from 1.2% in the pre-RAT era to 2.8% in the post-RAT period (P < 0.05). In addition, more successful removal of thrombus by aspiration led to less stenting (20% vs. 55% P < 0.05) in the post-RAT period thus avoiding the hazards of "triple therapy." Embolic infarction was more frequently associated with atrial fibrillation (55% vs. 8%), had higher mortality (17% vs. 4%), and had higher rates of embolic stroke (13% vs. 0.3%) when compared with atherosclerotic MI (all P < 0.05). CONCLUSIONS: Routine aspiration thrombectomy more readily identifies embolic infarction allowing more specific therapy and avoidance of stenting and triple anticoagulant therapy.

Left bundle branch block without concordant ST changes is rarely associated with acute coronary occlusion.

BACKGROUND: The Sgarbossa score has been used to identify acute myocardial infarction on ECG in the presence of LBBB but has relied on elevated CK-MB for validation rather than angiographic evidence of vessel occlusion. METHODS: We determined (a) the presence or absence of Sgarbossa criteria with concordant (S-con) or discordant (S-dis) ST changes, (b) the presence of acute coronary occlusion or likely recent occlusion on angiography and (c) the biochemical evidence of myocardial infarction (Troponin T >0.10 µg/L, Troponin I >1.0 µg/L) in patients field-triaged with suspected AMI and LBBB. RESULTS: Between April 2004 and March 2009, 102 patients had field ECGs transmitted by paramedics for triage--8 with S-con, 26 with S-dis and 68 with LBBB alone. Acute coronary occlusion was present in 8/8 with S-con but none of the S-dis or LBBB alone patients, and in all 8 S-con patients reperfusion resulted in resolution of S-con changes. Likely culprit lesions with TIMI 3 flow were found in 3 S-dis patients but stenting did not result in resolution of S-dis. LBBB did not resolve in any patient. Troponin was elevated in 26 patients--11 with occlusion or likely culprit lesions, 15 with non-ischaemic causes. CONCLUSIONS: In the absence of S-con, LBBB is not associated with acute coronary occlusion and should not be used as criteria for reperfusion therapy in myocardial infarction.

Field triage to primary angioplasty combined with emergency department bypass reduces treatment delays and is associated with improved outcome.

AIMS: We investigated the net benefit in the outcome of reducing treatment delay through field triage and emergency department (ED) bypass in patients with ST-elevation myocardial infarction (STEMI) treated with primary angioplasty. METHODS AND RESULTS: In a prospective registry study, consecutive patients with suspected STEMI were assigned to: (i) pre-hospital ECG and triage or (ii) ECG and triage at the closest ED, solely based on ambulance availability. Four district hospitals and one regional heart centre serviced the 890,000 population metropolitan area and primary angioplasty was the only reperfusion strategy employed. Baseline characteristics were similar in STEMI patients triaged in the field (108) and the EDs (193). Symptom onset to balloon times: 154 [inter-quartile range (IQR) 120-233) vs. 249 (IQR 184-405) min (P<0.001) and peak creatine kinase in early presenters (<2 h): 1435 (95 %CI: 904-1966) U/L vs. 2320 (95% CI: 1881-2762) U/L (P=0.009) were lower in field- than in ED-triaged patients. Mortality in the PCI treated were 1.1 and 8.2% [P=0.025, RR 0.14 (95% CI: 0.01-1.08)] and overall mortality were 1.9 and 7.3% [P=0.046, RR 0.26 (95% CI: 0.05-1.11)]. CONCLUSION: Field-triage and ED bypass were feasible means of reducing treatment delay in patients with suspected STEMI and resulted in smaller infarct size in early presenters and a trend towards a reduction in mortality.