Vignendra Ariyarajah

Late gadolinium enhancement cardiovascular magnetic resonance in genotyped hypertrophic cardiomyopathy with normal phenotype

A 35 year-old asymptomatic Caucasian female with a family history of hypertrophic cardiomyopathy (HCM) was referred for cardiologic evaluation. The electrocardiogram and transthoracic echocardiogram were normal. Cardiovascular magnetic resonance (CMR) was performed for further assessment of myocardial function and presence of myocardial scar. CMR showed normal left ventricular systolic size, measurements and function. However, there was extensive, diffuse late gadolinium enhancement (LGE) throughout the left ventricle. This finding was consistent with extensive myocardial scarring and was highly suggestive of advanced, non-ischemic cardiomyopathy. Genotyping showed a heterozygous mis-sense mutation (275G>A) in the cardiac troponin T (TNNT2) gene, which is causally associated with HCM. There have been no previous reports of such extensive, atypical pattern of myocardial scarring despite an otherwise structurally and functionally normal left ventricle in an asymptomatic individual with HCM. This finding has important implications for phenotype screening in HCM.

Interatrial Block: A Novel Risk Factor for Embolic Stroke?

Background: Interatrial block (IAB; P wave ≥110 ms) is highly prevalent and is strongly associated with atrial tachyarrhythmias and left atrial dysfunction, making it a potential embolic risk.

The Bachmann Bundle and interatrial conduction.

The cardiac conduction system (CCS) is responsible for generation and systematic conduction of cardiac impulses. The Bachmann Bundle (BB), considered one of its several accessory impulse-conducting pathways, plays a fundamental role in interatrial conduction. Delay in this pathway leads to prolongation of the P wave on the electrocardiogram (interatrial delay or block), which in turn is a precursor for atrial tachyarrhythmias, mainly atrial fibrillation and significant left atrial electromechanical dysfunction. As such, the magnitude of its sequelae has necessitated a flurry of investigations that have been targeted toward its prevention and management. Although current studies on the use of angiotensin-converting enzyme inhibitors and atrial pacing have indeed shown some promise, it would be shortsighted to overlook and circumvent the actual underlying lesion—BB abnormality. Thus, a thorough understanding of the CCS and interatrial conduction is essential. We review current literature on the BB and discuss potential mechanisms that affect its conduction.

Left atrial passive emptying function during dobutamine stress MR imaging is a predictor of cardiac events in patients with suspected myocardial ischemia.

OBJECTIVES The aim of this study was to determine the prognostic value of assessing left atrial function during dobutamine stress testing. BACKGROUND Left ventricular diastolic dysfunction precedes systolic wall motion abnormalities in the ischemic cascade. Severity of left ventricular diastolic function during cardiac stress is not characterized well by current clinical imaging protocols but may be an important prognostic factor. We hypothesized that abnormal early left atrial emptying measured during dobutamine stress cardiac magnetic resonance will reflect these diastolic changes and may be associated with cardiovascular outcomes. METHODS We enrolled 122 consecutive patients referred for dobutamine stress cardiac magnetic resonance for suspected myocardial ischemia. Left atrial volumes were retrospectively measured by the biplane area-length method at left ventricular end-systole (VOL(max)) and before atrial contraction (VOL(bac)). Left atrial passive emptying fraction defined by (VOL(max) - VOL(bac)) × 100%/VOL(max) and the absolute percent increase in left atrial passive emptying fraction during dobutamine stress (ΔLAPEF) were quantified. RESULTS Twenty-nine major adverse cardiac events (MACE) occurred during follow-up (median 23 months). By Kaplan-Meier analysis, patients with ΔLAPEF <10.8 (median) experienced higher incidence of MACE than did patients with a ΔLAPEF >10.8 (p = 0.004). By univariable analysis, ΔLAPEF was strongly associated with MACE (unadjusted hazard ratio for every 10% decrease = 1.56, p < 0.005). By multivariable analysis, every 10% decrease in ΔLAPEF carried a 57% increase in MACE, after adjustment to presence of myocardial ischemia and infarction. CONCLUSIONS Reduced augmentation of left atrial passive emptying fraction during dobutamine stress demonstrated strong association with MACE. We speculate that reduced left atrial passive emptying reserve during inotropic stress may represent underlying diastolic dysfunction and warrants further investigation.

Acute pericarditis: diagnostic cues and common electrocardiographic manifestations.

Acute pericarditis (AP) is basically a clinical diagnosis. Although specific electrocardiographic (ECG) manifestations may indeed point to its diagnosis, sole reliance on such findings in isolation of the clinical setting, however, is often the common pitfall that could lead to a misguided diagnosis. We briefly review the anatomy of the pericardium and the pathophysiology of pericarditis to highlight common signs and symptoms as well as clinical findings that may assist in the diagnosis of AP. We also feature the characteristic evolution of its ECG manifestations and point out some of its typical and atypical features to help better differentiate AP from commonly confused conditions.

Interatrial Block: The Pandemic Remains Poorly Perceived

Interatrial block (IAB; P duration ≥110 ms) is a common electrocardiogram abnormality, which in addition to reduced left atrial function predicts atrial fibrillation and other arrhythmias. P terminal force (Ptf) ± biphasic P in lead V1≥ the area of one small square on the grid also indicates left atrial abnormality, particularly left atrial enlargement, which is a strong correlate of IAB. Among 482 consecutively recorded electrocardiograms, IAB and Ptf were strongly and significantly correlated (χ2= 68.041; P ≤ 0.001). In conclusion, interatrial block exists in pandemic proportions in unselected hospital patients. Because of its pathologic implications it requires widespread attention which, heretofore, has been lacking.

The Association of Atrial Tachyarrhythmias with Isolated Atrial Amyloid Disease: Preliminary Observations in Autopsied Heart Specimens

Objective: Isolated atrial amyloidosis (IAA) is associated with atrial tachyarrhythmias. However, only a few studies have appraised atrial tachyarrhythmias and atrial depolarization abnormalities in connection with high-grade IAA. We conducted a collaborative retrospective study to assess this association. Methods: One hundred consecutive autopsied hearts were studied histologically for IAA. To increase the specificity for atrial depolarization abnormalities in this preliminary study, we excluded those specimens with intermediate amyloid involvement, i.e. IAA grades 1 and 2 (grade 0 = absent or trivial deposits; grade 1 = small deposits; grade 2 = moderate deposits; grade 3 = dense, large deposits). We then screened for baseline, premortem electrocardiograms (ECGs) to assess rhythm. In those with sinus rhythm, the P wave axis, duration, dispersion and terminal force in V1 were determined under magnification. Results: Of the 27 premortem ECGs corresponding to the autopsy specimens with grades 3 (sample) or 0 (controls) IAA, 9 showed sinus rhythm, 13 showed atrial fibrillation, 1 showed atrial flutter and 4 were uninterpretable. Fourteen autopsied hearts (52%) were positive for grade 3 IAA. Ten of those had atrial tachyarrhythmias (9 atrial fibrillation and 1 atrial flutter) compared to 4 of the 13 hearts with grade 0 IAA (72 vs. 31%, respectively; p = 0.03). Although there was excellent interobserver agreement using intraclass correlation coefficients, there were no significant differences in P wave measurements among the small number of patients with sinus rhythm for grade 3 versus grade 0 IAA. Conclusion: In a collaborative, preliminary, pilot assessment of autopsied hearts for which premortem ECGs were necessarily screened retrospectively, significantly more hearts with high-grade IAA were associated with atrial tachyarrhythmias compared to those with low-grade IAA. A larger study with an appropriately matched autopsy control group is needed to confirm these and previous observations.

Potential Factors That Affect Electrocardiographic Progression of Interatrial Block

Introduction: Interatrial block (IAB; P wave ≥ 110 ms) is associated with atrial tachyarrhythmias and left atrial electromechanical dysfunction. This subtle abnormality is highly prevalent and may exist as partial (pIAB) or advanced IAB (aIAB). Indeed, theoretically pIAB could progress to aIAB with worsening interatrial conduction over time. However, this has been poorly investigated. We retrospectively appraised this phenomenon and also evaluated the influence of common clinical factors such as coronary artery disease (CAD), hypertension (HTN), and use of antihypertensive medications.

The utility of cardiovascular magnetic resonance in constrictive pericardial disease.

Cardiovascular magnetic resonance (CMR) has a high diagnostic accuracy for constrictive pericarditis (CP). CMR allows for high-resolution imaging of the pericardium and associated structures in any imaging plane compared with that provided by other imaging modalities. We briefly discuss the specific quantitative and qualitative CMR sequences that can be tailored to answer the clinical questions pertaining to CP, where the diagnostic yield has been proven when characteristic CMR features of CP are present. Such features allow for differentiation of CP from restrictive cardiomyopathy, where the clinical differentiation between the 2 can often be challenging.

Clinician underappreciation of interatrial block in a general hospital population.

Introduction: Interatrial block (IAB; P wave ≧110 ms), a conduction delay between the right and left atria (LA), is highly prevalent and strongly associated with atrial tachyarrhythmias, LA electromechanical dysfunction as well as a risk of embolism. Nonetheless, clinicians’ underappreciation of its existence and sequelae remains. We appraised this issue in a general hospital population. Methods: From the database of 730 12-lead electrocardiograms (ECGs) of patients aged 17–98 years (mean age 67.80 years; female patients 53.56%) in a tertiary care teaching general hospital, we recorded the computer-generated diagnostic readings of the ECGs and also the official cardiologist and hospitalist ECG interpretations and documentations. For increased sensitivity and specificity, and because the mode P wave duration in IAB is 120 ms, P waves ≧120 ms in any lead were used to diagnose IAB. Results: Six hundred and fifty-three ECGs (89.45%) showed sinus rhythm, and of those, IAB was documented on 309 ECGs (47.32%). LA enlargement was cited 29 times (3.97%), while possible LA enlargement and biatrial enlargement were cited 17 (2.32%) and 6 times (0.82%), respectively. One cardiologist’s ECG interpretation documented IAB (0.32%), but none of the other medical staff diagnosed IAB or abnormal P wave duration. Conclusion: This study demonstrates to extremes how IAB went undiagnosed in a general hospital population. Until more awareness of IAB is cultivated, such ignorance of the existence and sequelae of IAB could continue. Configuring ECG software to include P wave durations in computer-generated ECG readings could be useful in aiding diagnosis.