New algorithm effectively diagnoses acute MI in left bundle branch block
Researchers in Spain reported they validated the diagnostic accuracy of the BARCELONA algorithm for acute MI among patients with suspected MI and left bundle branch block who were referred for primary PCI.
“Patients with left bundle branch block referred for primary PCI are the target population that could benefit the most from an improved electrocardiographic diagnosis of acute MI,” Andrea Di Marco, MD, in the arrhythmia unit of the Heart Disease Institute at Bellvitge University Hospital in Barcelona, Spain, and colleagues wrote. “Because of the lack of a reliable electrocardiographic diagnosis of acute MI, these patients are often overtreated. Indeed, in our study, 63% of patients were unnecessarily exposed to an emergent reperfusion protocol, which has inherent risks and an elevated economic cost.”
This study, which was published in the Journal of the American Heart Association, was designed to assess whether the accuracy of acute MI diagnosis in the presence of left bundle branch block (LBBB) with ECG improved when variables such as concordant ST depression in any ECG lead and the occurrence of discordant and disproportionate ST deviation in leads with low-voltage QRS complexes were considered.
For this retrospective cohort study of the BARCELONA algorithm, researchers included a derivation cohort of 163 patients who were referred before 2015 (61 with acute MI), a validation cohort of 107 patients with suspected acute MI and LBBB who were referred for PCI between 2015 and 2018 (40 with acute MI) and a control group of 214 patients without suspected MI.
Researchers found that the BARCELONA algorithm was positive in the presence of ST deviation of at least 1 mm (0.1 mV) on the ECG concordant with QRS polarity, in any lead.
The algorithm was also positive in the presence of ST deviation of at least 1 mm (0.1 mV) on the ECG discordant with the QRS, in leads with max voltage no greater than 6 mm (0.6 mV).
“In patients with LBBB, it has been demonstrated that acute ischemia is associated with an increase in the magnitude of ST deviations discordant with QRS polarity so that they become disproportionately greater than would be expected by the voltage of the QRS in the corresponding lead,” the researchers wrote. “By using a new approach, we could identify a max (R|S) voltage of 6 mm (0.6 mV) as the best cutoff for disproportionate discordant ST deviations 1 mm (0.1 mV) suggestive of acute MI.”
High sensitivity and specificity
In addition, the algorithm achieved the highest sensitivity (93% to 95%), specificity (89% to 94%), negative predictive value (96% to 97%), efficiency (91% to 94%) and area under the receiver operating characteristic curve (0.92 to 0.93), among both the derivation and the validation groups compared with previous rules such as Sgarbossa score and Smith-modified Sgarbossa scores (P < .01).
“The possibility to achieve a reliable electrocardiographic diagnosis of acute MI in patients with LBBB would represent a major step forward,” the researchers wrote. “If our results are confirmed by other groups, the BARCELONA algorithm could be integrated into a wider clinical algorithm, to optimize the diagnosis and treatment of patients with LBBB and suspected acute MI.”
Assessment in an independent population needed
“The high sensitivity and specificity of the new BARCELONA algorithm require to be assessed in an independent population, either manually or with automated techniques,” Peter W. Macfarlane, DSc, electrocardiologist in the Electrocardiology Core Lab at Glasgow Royal Infirmary, U.K., wrote in a related editorial. “It sometimes happens that criteria developed in one center do not perform so well when evaluated in another center. Nevertheless, few ECG criteria have been shown through the years to be the order of 93% to 94% sensitive and specific and only time will tell whether the outstanding performance of the criteria set out in the article of Di Marco et al will stand the test of independent assessment.”
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