The accuracy of electrocardiographic Q waves for the detection of prior myocardial infarction as assessed by a novel standard of reference

Electrocardiographic abnormalities and NT-proBNP levels at long-term follow-up of patients with dyspnea after pulmonary embolism

OBJECTIVES

Electrocardiogram (ECG) and measurement of plasma brain natriuretic peptides (BNP) are established markers of right ventricular dysfunction (RVD) in the setting of acute pulmonary embolism (PE) but their value at long-term follow-up is largely unknown. The purpose of this prospective study was to determine the prevalence of ECG abnormalities, describe levels of N-terminal proBNP (NT-proBNP), and establish their association with dyspnea at long-term follow-up after PE.

DESIGN

All Swedish patients diagnosed with acute PE in 2005 (n = 5793) were identified through the Swedish National Patient Registry. Surviving patients in 2007 (n = 3510) were invited to participate. Of these, 2105 subjects responded to a questionnaire about dyspnea and comorbidities. Subjects with dyspnea or risk factors for development of chronic thromboembolic pulmonary hypertension were included in the study in a secondary step, which involved collection of blood samples and ECG registration.

RESULTS

Altogether 49.3% had a completely normal ECG. The remaining participants had a variety of abnormalities, 7.2% had atrial fibrillation/flutter (AF). ECG with any sign of RVD was found in 7.2% of subjects. Right bundle branch block was the most common RVD sign with a prevalence of 6.4%. An abnormal ECG was associated with dyspnea. AF was associated with dyspnea, whereas ECG signs of RVD were not. 61.2% of subjects had NT-proBNP levels above clinical cut-off (>125 ng/L). The degree of dyspnea did not associate independently with NT-proBNP levels.

CONCLUSIONS

We conclude that the value of ECG and NT-proBNP in long term follow-up after PE lies mostly in differential diagnostics.

Diagnostic value of the electrocardiogram in the assessment of prior myocardial infarction

Background

The best available imaging technique for the detection of prior myocardial infarction (MI) is cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE). Although the electrocardiogram (ECG) still plays a major role in the diagnosis of prior MI, the diagnostic value of the ECG remains uncertain. This study evaluates the diagnostic value of the ECG in the assessment of prior MI.

Methods

In this retrospective study, data from electronic patient files were collected of 1033 patients who had undergone CMR with LGE between January 2014 and December 2017. After the exclusion of 59 patients, the data of 974 patients were analysed. Twelve-lead ECGs were blinded and evaluated for signs of prior MI by two cardiologists separately. Disagreement in interpretation was resolved by the judgement of a third cardiologist. Outcomes of CMR with LGE were used as the gold standard.

Results

The sensitivity of the ECG in the detection of MI was 38.0% with a 95% confidence interval (CI) of 31.6–44.8%. The specificity was 86.9% (95% CI 84.4–89.1%). The positive and negative predictive value were 43.6% (95% CI 36.4–50.9%) and 84.0% (95% CI 81.4–86.5%) respectively. In 170 ECGs (17.5%), the two cardiologists disagreed on the presence or absence of MI. Inter-rater variability was moderate (κ 0.51, 95% CI 0.45–0.58, p < 0.001).

Conclusion

The ECG has a low diagnostic value in the detection of prior MI. However, if the ECG shows no signs of prior MI, the absence of MI is likely. This study confirms that a history of MI should not be based solely on an ECG.

Association of Recognized and Unrecognized Myocardial Infarction With Depressive and Anxiety Disorders in 125,988 Individuals: A Report of the Lifelines Cohort Study

OBJECTIVE

No previous study has focused on recognition of myocardial infarction (MI) and the presence of both depressive and anxiety disorders in a large population-based sample. The aim of this study was to investigate the association of recognized MI (RMI) and unrecognized MI (UMI) with depressive and anxiety disorders.

METHODS

Analyses included 125,988 individuals enrolled in the Lifelines study. Current mental disorders according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) were assessed with the Mini-International Neuropsychiatric Interview. UMI was detected using electrocardiogram in participants who did not report a history of MI. The classification of RMI was based on self-reported MI history together with the use of either antithrombotic medications or electrocardiogram signs of MI. Analyses were adjusted for age, sex, smoking, somatic comorbidities, and physical health-related quality of life as measured by the RAND 36-Item Health Survey in different models.

RESULTS

Participants with RMI had significantly higher odds of having any depressive and any anxiety disorder as compared with participants without MI (depressive disorder: odds ratio [OR] = 1.86, 95% confidence interval [CI] = 1.38-2.52; anxiety disorder: OR = 1.60, 95% CI = 1.32-1.94) after adjustment for age and sex. Participants with UMI did not differ from participants without MI (depressive disorder: OR = 1.60, 95% CI = 0.96-2.64; anxiety disorder: OR = 0.73, 95% CI = 0.48-1.11). After additional adjustment for somatic comorbidities and low physical health-related quality of life, the association between RMI with any depressive disorder was no longer statistically significant (OR = 1.18; 95% CI =0.84-1.65), but the association with any anxiety disorder remained (OR = 1.27, 95% CI = 1.03-1.57).

CONCLUSIONS

Recognition of MI seems to play a major role in the occurrence of anxiety, but not depressive, disorders.

Sex-Based Differences in Unrecognized Myocardial Infarction

Background

Myocardial infarction is an important cause of morbidity and mortality in both men and women. Atypical or the absence of symptoms, more prevalent among women, may contribute to unrecognized myocardial infarctions and missed opportunities for preventive therapies. The aim of this research is to investigate sex‐based differences of undiagnosed myocardial infarction in the general population.

Methods and Results

In the Lifelines Cohort Study, all individuals ≥18 years with a normal baseline ECG were followed from baseline visit till first follow‐up visit (≈5 years, n=97 203). Individuals with infarct‐related changes between baseline and follow‐up ECGs were identified. The age‐ and sex‐specific incidence rates were calculated and sex‐specific cardiac symptoms and predictors of unrecognized myocardial infarction were determined. Follow‐up ECG was available after a median of 3.8 (25th and 75th percentile: 3.0–4.6) years. During follow‐up, 198 women experienced myocardial infarction (incidence rate 1.92 per 1000 persons‐years) compared with 365 men (incidence rate 3.30; P<0.001 versus women). In 59 (30%) women, myocardial infarction was unrecognized compared with 60 (16%) men (P<0.001 versus women). Individuals with unrecognized myocardial infarction less often reported specific cardiac symptoms compared with individuals with recognized myocardial infarction. Predictors of unrecognized myocardial infarction were mainly hypertension, smoking, and higher blood glucose level.

Conclusions

A substantial proportion of myocardial infarctions are unrecognized, especially in women. Opportunities for secondary preventive therapies remain underutilized if myocardial infarction is unrecognized.

Electrocardiographic unrecognized myocardial infarction does not improve prediction of cardiovascular events beyond traditional risk factors. The Tromsø Study

Background Unrecognized myocardial infarction (MI) is a frequent and intriguing entity associated with a similar risk of death as recognized MI. Previous studies have not fully addressed whether the poor prognosis is explained by traditional cardiovascular risk factors. We investigated whether electrocardiographically detected unrecognized MI was independently associated with cardiovascular events and death and whether it improved prediction for future MI in a general population. Design Prospective cohort study. Methods We studied 5686 women and men without clinically recognized MI at baseline in 2007-2008. We assessed the risk of future MI, stroke and all-cause mortality in persons with unrecognized MI compared with persons with no MI during 31,051 person-years of follow-up. Results In the unadjusted analyses, unrecognized MI was associated with increased risk of future recognized MI (hazard ratio 1.84, 95% confidence interval (CI) 1.15-2.96) and all-cause mortality (hazard ratio 1.78, 95% CI 1.21-2.61), but not stroke (hazard ratio 1.09, 95% CI 0.56-2.17). The associations did not remain significant after adjustment for traditional risk factors (hazard ratio 1.25, 95% CI 0.76-2.06 and hazard ratio 1.38, 95% CI 0.93-2.05) for MI and all-cause mortality respectively. Unrecognized MI did not improve risk prediction for future recognized MI using the Framingham Risk Score ( p = 0.96) or the European Systematic COronary Risk Evaluation ( p = 0.65). There was no significant sex interaction regarding any of the endpoints. Conclusion Electrocardiographic unrecognized MI was not significantly associated with future risk of MI, stroke or all-cause mortality in the general population after adjustment for the traditional cardiovascular risk factors, and it did not improve prediction of future MI.

Prevalence of electrocardiographic unrecognized myocardial infarction and its association with mortality

BACKGROUND

Identifying unrecognized myocardial infarction (MI) is important for secondary prevention. The aim of this study is to determine the prevalence and correlates of unrecognized MI and the association with mortality in the general population.

METHODS

All participants ≥18years participating in the Lifelines population, a three-generation Cohort Study and Biobank, were included (n=152,180). Participants with unrecognized MI were matched with controls without MI (1:2) based on age and gender. Unrecognized MI was defined when no history of MI was reported in combination with electrocardiographic (ECG) signs corresponding to MI. A history of MI was defined as a reported history of MI in combination with ECG signs and/or the use of antithrombotic medication.

RESULTS

MI was present in 1881(1.2%) of participants and was unrecognized in 431 (22.9%) participants. Under the age of 50years, percentages of unrecognized MI relative to the total amount of MI were 34% and 55% in men and women respectively. Compared to recognized MI, classical cardiovascular risk factors were less prevalent in participants with unrecognized MI. During a median follow- up time of 5, 4 and 4years, 4.4%, 6.4% and 2.2% of participants with unrecognized MI, recognized MI and without MI died, respectively. In a multivariable logistic regression unrecognized MI was an independent predictor of death.

CONCLUSIONS

The prevalence of unrecognized MI is substantial and classical cardiovascular risk factors are less prevalent in participants with unrecognized MI. Nevertheless, unrecognized MI is associated with mortality. Risk stratification and early diagnosis is necessary to reduce the morbidity and mortality after MI.

Does the presence of Q waves on the EKG accurately predict prior myocardial infarction when compared to cardiac magnetic resonance using late gadolinium enhancement? A cross-population study of noninfarct vs infarct patients

BACKGROUND

We hypothesize that infarct detection by electrocardiogram (EKG) is inaccurate as compared with detection by magnetic resonance imaging and is potentially independent of infarct vs noninfarct status. This might have implications for societies in which initial cardiovascular testing is uniformly EKG.

OBJECTIVE

This study aimed to relate EKG-defined scar to cardiovascular magnetic resonance imaging (CMR)-defined scar independent of the underlying myocardial pathology.

METHODS

A total of 235 consecutive patients who underwent CMR-late gadolinium enhancement (LGE) with simultaneous EKG were screened for Q waves and compared with patients with a positive LGE pattern. The patients were divided into 3 groups: (1) patients with a positive infarct LGE pattern (LGE+/+; herein defined as LGE+), (2) patients with a noninfarct LGE pattern (LGE+/-), and (3) patients with a negative LGE pattern (LGE-).

RESULTS

While 139 of 235 patients (59%) were either LGE+ or LGE+/-, pathological Q waves were present in only 74 of 235 patients (31%). However, of these LGE+ or LGE+/- patients, only 76 (32%) had an infarct LGE pattern representing little overlap between the presence of LGE+ and Q waves. EKG sensitivity and specificity to detect infarct: 66% and 85%, respectively. However, of 24 of 74 patients (32%) with Q waves on the EKG, 66% were LGE+/- and 34% were LGE-. Importantly, 3-dimensional volume of myocardial scar was far more predictive of a Q wave than of scar transmurality.

CONCLUSION

EKG-defined scar, while ubiquitous for an infarct, has low sensitivity than CMR-LGE-defined scar. Unexpectedly, a significant number of pathological Q waves had absent infarct etiology, indicating high false positivity. Similarly, underrecognition of bona fide myocardial infarction frequently occurs, while 3-dimensional CMR volume of myocardial scar is far more predictive of a Q wave than of scar transmurality. This suggests that the well-regarded EKG may be a disservice when applied on a population basis, leading to inappropriate over or under downstream testing with wide socioeconomic implications.

Prognostic significance of silent myocardial infarction in newly diagnosed type 2 diabetes mellitus: United Kingdom Prospective Diabetes Study (UKPDS) 79

BACKGROUND

We aimed to determine the prevalence of silent myocardial infarction (SMI) in people with newly diagnosed type 2 diabetes mellitus and its relationships to future myocardial infarction (MI) and all-cause mortality.

METHODS AND RESULTS

We examined data from the 5102 patients in the 30-year UK Prospective Diabetes Study (UKPDS) and used Cox proportional hazards regression to examine outcomes by SMI status. Of 1967 patients with complete baseline data, 326 (16.6%) had ECG evidence of SMI (Minnesota codes 1.1 or 1.2) at enrollment. Those with SMI were more likely to be older, female, sedentary, and nonsmokers compared with those without SMI. Their mean blood pressure was greater despite more intensive antihypertensive treatment; they were more likely to be taking aspirin and lipid-lowering therapy; and they had a greater prevalence of microangiopathy. Fully adjusted hazard ratios for those with versus those without SMI in multivariate models that included UKPDS Risk Engine variables were 1.58 (95% confidence interval, 1.22-2.05) for fatal MI and 1.31 (95% confidence interval, 1.10-1.56) for all-cause mortality. Hazard ratios for first fatal or nonfatal MI and for first nonfatal MI were nonsignificant. The net reclassification index showed no improvement when SMI was added to these models, and the integrated discrimination index showed that SMI marginally improved the prediction of fatal MI and all-cause mortality.

CONCLUSIONS

About 1 in 6 UKPDS patients with newly diagnosed type 2 diabetes mellitus had evidence of SMI, which was independently associated with an increased risk of fatal MI and all-cause mortality. However, identification of SMI does not add substantively to current UKPDS Risk Engine predictive variables.

CLINICAL TRIAL REGISTRATION

URL: http://www.controlled-trials.com. Identifier: ISRCTN number 75451837.

Optimized electrocardiographic criteria for prior inferior and anterior myocardial infarction

BACKGROUND AND PURPOSE

The first purpose of the study was to optimize empirically the detection of prior inferior myocardial infarction (IMI) and prior anterior myocardial infarction (AMI) by electrocardiogram (ECG). The second purpose was to compare the diagnostic performances of the new criteria with those of 3 widely used commercial diagnostic ECG algorithms.

MATERIALS AND METHODS

We analyzed the digital ECG data from 1138 subjects with suspected coronary artery disease in whom the presence or absence of prior IMI or AMI was documented by coronary angiography and left ventriculography. We used receiver operating characteristic curves to develop the new criteria for prior IMI and AMI using a training set of 562 subjects and then tested their diagnostic performances using a separate test set of 576 subjects. In both the training and test sets, we used χ(2) test to compare the performances of the new criteria with those of 3 commercial computerized diagnostic algorithms.

RESULTS

The best criterion for prior IMI was the algebraic sum of the Q and T amplitudes in leads III and aVF. Its sensitivities/specificities were 71%/98% and 74%/98% in the training and test sets, respectively. The best criterion for prior AMI was the algebraic sum of the Q, R, and T amplitudes minus the Q duration in leads V(2), V(3), and V(4). Its sensitivities/specificities were 68%/98% and 65%/98% in the training and test sets, respectively. In both the training and test sets, these diagnostic performances were generally superior to those of the 3 commercial algorithms.

CONCLUSIONS

Using digital ECG data, we developed and tested new criteria for prior IMI and AMI whose diagnostic performances are generally superior to each of 3 widely used commercial ECG diagnostic algorithms.

A cardiac magnetic resonance imaging study of electrocardiographic Q waves in type 2 diabetes: the Fremantle Diabetes Study

To investigate the evolution and significance of Q waves in type 2 diabetes, we studied 36 patients of mean (+/-S.D.) age 69.9+/-7.1 years from the longitudinal observational Fremantle Diabetes Study (FDS). All had (i) neither history/symptoms of coronary heart disease (CHD) nor pathological Q waves at FDS recruitment between 1993 and 1996, (ii) five consecutive annual assessments by FDS close-out in 2001, and (iii) contrast-enhanced cardiac magnetic resonance imaging in 2005. At this latter assessment, there were (i) 9 with no history of CHD or Q waves during follow-up (Group 1), (ii) 13 with Q waves on >/=1 electrocardiogram but no CHD history/symptoms (Group 2), and (iii) 14 with CHD history/symptoms irrespective of electrocardiographic status (Group 3). Of 20 episodes of new Q waves in 17 Group 2 or Group 3 patients during FDS follow-up, 17 (85%) resolved within 2 years. A myocardial infarction (MI) was detected by CMR in three patients (8.3%; one subendocardial in Groups 1 and 3, one non-full-thickness in Group 3) but these did not correlate with electrocardiographic appearances. Q waves may have unreliable pathological significance in type 2 diabetes, including as a marker of silent MI.

Lack of sensitivity of the electrocardiogram for detection of old myocardial infarction: a cardiac magnetic resonance imaging study

BACKGROUND

The presence of Q waves in the electrocardiogram (ECG) has been used as a marker of prior myocardial infarction (MI). Its accuracy, however, is uncertain. The purpose of this study is to determine the accuracy of an ECG to detect prior MI compared with a novel criterion standard.

METHODS

This study conducted retrospective inclusion with de novo analysis of ECG and cardiac magnetic resonance (CMR) by independent blinded readers in a single-institution setting. The population consisted of a consecutive sample of 146 patients referred for CMR for evaluation of myocardial viability and necrosis. Q/QS waves on ECG were defined as per Minnesota Code criteria. Myocardial scar was quantified and localized by CMR delayed contrast hyperenhancement and assumed as criterion standard. Sensitivity, specificity, and predictive values of ECG were calculated for different scar sizes (>1%, >15%, and >30% of the myocardium) and location (global, anterior, inferior, and lateral walls).

RESULTS

Sensitivity was 48.4%; specificity, 83.5; positive predictive accuracy, 72.0%; and negative predictive accuracy, 64.2%. Sensitivity improved when only large infarcts were considered (64.2%), but specificity decreased to 72.7%. Sensitivity for detecting isolated anterior or inferior wall scars was similar, but isolated lateral wall scar was rarely identified (14.3%). When all 3 walls were involved, sensitivity was still low at 57.9%.

CONCLUSIONS

The lack of sensitivity and the resulting low negative predictive value of Q/QS criteria seriously limit its accuracy as a marker of prior MI.