Pain modulation efficiency delays seeking medical help in patients with acute myocardial infarction

Association between pre-hospital chest pain severity and myocardial injury in ST elevation myocardial infarction: A post-hoc analysis of the AVOID study

BACKGROUND

We sought to determine if an association exists between prehospital chest pain severity and markers of myocardial injury.

METHODS AND RESULTS

Patients with confirmed ST elevation myocardial infarction (STEMI) treated by emergency medical services were included in this retrospective cohort analysis of the AVOID study. The primary endpoint was the association of pre-hospital initial chest pain severity, cardiac biomarkers and infarct size based on cardiac magnetic resonance imaging. Groups were categorized based on moderate to severe chest pain (numerical rating scale pain ≥ 5/10) or less than moderate severity to compare procedural and clinical outcomes. 414 patients were included in the analysis. There was a weak correlation between initial pre-hospital chest pain severity and peak creatine kinase (r = 0.16, p = 0.001) and peak cardiac troponin I (r = 0.14, p = 0.005). Both were no longer significant after adjusting for known confounders. There was no association between moderate to severe chest pain on arrival and major adverse cardiac events at 6 months (20% vs. 14%, p=0.12). There was a weak correlation between history of ischemic heart disease (r = 0.16, p = 0.001), percutaneous coronary intervention (r = 0.16, p = 0.001), left anterior descending artery (r = 0.12, p = 0.012) as the culprit vessel and a weak negative correlation between age (r = -0.14, p = 0.039) and chest pain.

CONCLUSION

Only a weak association between pre-hospital chest pain severity and markers of myocardial injury was identified, supporting more judicious use of opioid analgesia with a focus on patient comfort.

Low Pain Tolerance Is Associated With Coronary Angiography, Coronary Artery Disease, and Mortality: The Tromsø Study

Background

The initial presentation to coronary angiography and extent of coronary artery disease (CAD) vary greatly among patients, from ischemia with no obstructive CAD to myocardial infarction with 3‐vessel disease. Pain tolerance has been suggested as a potential mechanism for the variation in presentation of CAD. We aimed to investigate the association between pain tolerance, coronary angiography, CAD, and death.

Methods and Results

We identified 9576 participants in the Tromsø Study (2007–2008) who completed the cold‐pressor pain test, and had no prior history of CAD. The median follow‐up time was 10.4 years. We applied Cox‐regression models with age as time‐scale to calculate hazard ratios (HR). More women than men aborted the cold pressor test (39% versus 23%). Participants with low pain tolerance had 19% increased risk of coronary angiography (HR, 1.19 [95% CI, 1.03–1.38]) and 22% increased risk of obstructive CAD (HR, 1.22 [95% CI, 1.01–1.47]) adjusted by age as time‐scale and sex. Among women who underwent coronary angiography, low pain tolerance was associated with 54% increased risk of obstructive CAD (HR, 1.54 [95% CI, 1.09–2.18]) compared with high pain tolerance. There was no association between pain tolerance and nonobstructive CAD or clinical presentation to coronary angiography (ie, stable angina, unstable angina, and myocardial infarction). Participants with low pain tolerance had increased risk of mortality after adjustment for CAD and cardiovascular risk factors (HR, 1.40 [95% CI, 1.19–1.64]).

Conclusions

Low cold pressor pain tolerance is associated with a higher risk of coronary angiography and death.

Resting blood pressure modulates chest pain intensity in patients with acute myocardial infarction

Introduction and Objectives

Animal models and human studies show that resting blood pressure (BP) is inversely associated with pain sensitivity. The phenomenon of "hypertension-associated hypoalgesia" was proposed as a possible explanation for the intervariability in pain perception. Given that a portion of patients with acute myocardial infarction (AMI) do not experience significant pain, we used the model of severe cardiac ischemia to explore whether BP affects the intensity of chest pain.

Methods

Patients with AMI admitted to the cardiac intensive care unit with coronary catheterization-proven completely occluded coronary artery were included (n = 67). Resting BP at admission and 5 days after AMI was obtained. Participants reported chest pain intensity and underwent psychophysical evaluation including pain ratings for pressure, heat, and pinprick stimuli as well as temporal summation and conditioned pain modulation paradigms.

Results

Patients with lower systolic BP (≤120 mm Hg) vs higher (≥140 mm Hg) reported higher chest pain scores at symptom onset (82.3 vs 61.7, P = 0.048) and during peak AMI (82.8 vs 57.5, P = 0.019). Higher pain ratings in response to pinprick stimulus were associated with lower BP at admission (analysis of variance P = 0.036). Patients with hypertension demonstrated lower pain sensitivity in response to pressure stimulation (531.7 ± 158.9 kPa/s vs 429.1 ± 197.4). No significant associations were observed between BP and the other assessed psychophysical measures.

Conclusion

Study findings reinforce the phenomenon of hypertension-associated hypoalgesia through characterization of the association between BP and clinical pain experiences at onset and during AMI in a model of acute clinical pain.

Outcomes following non-life-threatening orthopaedic trauma: Why are they considered to be so poor?

The purpose of this review article is to assess the current literature on the outcomes of simple orthopaedic trauma. Simple trauma is defined as the fracture or injury of one limb due to an acute event. Fractures are the most common cause of hospitalized trauma in Australia and associated with multiple social, psychological and physical consequences for patients. The literature to date suggests that there are multiple factors leading to relatively poor outcomes following simple trauma, modifiable and non-modifiable. The most oft cited are older age, lower educational status, being injured at work, injury severity score, pre-existing disease, workers compensation, litigation and pain at initial assessment. Additional psychological risk factors quoted attribute to the injury to an external source and the use of passive coping strategies. This review aims to summarise the relevant literature relating to these risk factors and give direction to improving outcomes and future research into this important area.

Pain Tolerance in Persons With Recognized and Unrecognized Myocardial Infarction: A Population-Based, Cross-Sectional Study

BACKGROUND

Unrecognized myocardial infarction (MI) is a prevalent condition associated with a similar risk of death as recognized MI. It is unknown why some persons experience MI with few or no symptoms; however, one possible explanation is attenuated pain sensitivity. To our knowledge, no previous study has examined the association between pain sensitivity and recognition of MI.

METHODS AND RESULTS

We conducted a population-based cross-sectional study with 4849 included participants who underwent the cold pressor test (a common experimental pain assay) and ECG. Unrecognized MI was present in 387 (8%) and recognized MI in 227 (4.7%) participants. Participants with unrecognized MI endured the cold pressor test significantly longer than participants with recognized MI (hazard ratio for aborting the cold pressor test, 0.64; CI, 0.47-0.88), adjusted for age and sex. The association was attenuated and borderline significant after multivariable adjustment. The association between unrecognized MI and lower pain sensitivity was stronger in women than in men, and statistically significant in women only, but interaction testing was not statistically significant (P for interaction=0.14).

CONCLUSIONS

Our findings suggest that persons who experience unrecognized MI have reduced pain sensitivity compared with persons who experience recognized MI. This may partially explain the lack of symptoms associated with unrecognized MI.