Recent Advances in the Diagnosis of Fascicular Blocks

Left posterior fascicular block due to high-dose interleukin-2

OBJECTIVE

To report a case of reversible left posterior fascicular block (LPFB) associated with high-dose interleukin-2 (IL-2) therapy.

CASE SUMMARY

A 50-year-old white, nonsmoking male with a history of hypertension, hyperlipidemia, paroxysmal atrial fibrillation, and hypothyroidism had been recently diagnosed with metastatic clear cell-type renal cell carcinoma. He was started on high-dose IL-2 therapy (600,000 IU/kg/dose by 15-min intravenous infusion every 8 h for up to 14 consecutive doses over 5 days, as tolerated). He developed new-onset LPFB after the second dose of IL-2, which was diagnosed electrocardiographically with right axis deviation; deep S waves in lead I; and qR waves in leads II, III, and aVF. He denied chest pain, palpitations, or syncope. The LPFB resolved 18 hours after discontinuation of IL-2 without any potential complications or delay of hospital discharge. The patient completed 9 of 14 doses of IL-2 therapy. Similar electrocardiogram changes were noticed during 2 subsequent cycles of high-dose IL-2 treatment, both of which resolved spontaneously.

DISCUSSION

High-dose IL-2 is a Food and Drug Administration-approved biological agent used as monotherapy for the treatment of metastatic renal cell carcinoma and metastatic melanoma. Capillary leak syndrome has been associated with IL-2 therapy and many of its cardiac and noncardiac toxicities. In our patient, LPFB was observed as a reversible adverse reaction to high-dose IL-2 therapy. The Naranjo probability scale indicates a probable relationship between LPFB and high-dose IL-2 in this patient. LPFB has not previously been reported as an adverse reaction associated with high-dose IL-2 therapy.

CONCLUSIONS

LPFB may be a reversible cardiac complication associated with high-dose IL-2 therapy. Healthcare professionals should be aware of this potential adverse effect.

The prognostic significance of intermediate QRS prolongation in acute myocardial infarction

Complete right and left bundle branch block and advanced atrioventricular block present on admission electrocardiograms of patients with acute myocardial infarction, are associated with poor short and long-term outcome. Little is known about the impact of intermediate QRS prolongation (0.09-0.11 s) on the prognosis of acute myocardial infarction. In this study, among 1100 consecutive patients with acute myocardial infarction treated with thrombolysis, the QRS duration on admission electrocardiogram was <0.09 s in 536 (48%) patients, between 0.09 and 0.11 s in 496 (45%) patients and >0.11 s in 78 (7%) patients. QRS duration was strongly associated with 7-day (0.6%, 6%,18%, P<0.001), 30-day (1%, 8%, 22%, P<0.001) and 1-year (3%, 11%, 26%, P<0.001) all-cause mortality. After adjustment for significant variables associated with 1-year mortality, including age, female gender, diabetes mellitus, systemic hypertension, previous myocardial infarction, anterior myocardial infarction and Killip class> or =2 on admission, both levels of QRS prolongation remained significant independent predictors of short and long-term all-cause mortality.

Acute myocardial infarction and complete bundle branch block at hospital admission: clinical characteristics and outcome in the thrombolytic era. GUSTO-I Investigators. Global Utilization of Streptokinase and t-PA [tissue-type plasminogen activator] for Occluded Coronary Arteries

OBJECTIVES

We sought to assess the outcome of patients with acute myocardial infarction (MI) and bundle branch block in the thrombolytic era.

BACKGROUND

Studies of patients with acute MI and bundle branch block have reported high mortality rates and poor overall prognosis.

METHODS

The North American population with acute MI and bundle branch block enrolled in the Global Utilization of Streptokinase and t-PA [tissue-type plasminogen activator] for Occluded Coronary Arteries (GUSTO-I) trial was matched by age and Killip class with an equal number of GUSTO-I patients without conduction defects.

RESULTS

Of all 26,003 North American patients in GUSTO-I, 420 (1.6%) had left (n = 131) or right (n = 289) bundle branch block. These patients had higher 30-day mortality rates than matched control subjects (18% vs. 11%, p = 0.003, odds ratio [OR] 1.8) and were more likely to experience cardiogenic shock (19% vs. 11%, p = 0.008, OR 1.78) or atrioventricular block/asystole (30% vs. 19%, p < 0.012, OR 1.57) and to require ventricular pacing (18% vs. 11%, p = 0.006, OR 1.73). Bundle branch block also carried an independent 53% higher risk for 30-day mortality. Thirty-day mortality rates for patients with complete, partial and no reversion of the bundle branch block were 8%, 12% and 20%, respectively (two-tailed chi-square test for trend 5.61, p = 0.02, OR 0.34 for complete reversion, OR 0.55 for partial reversion).

CONCLUSIONS

Bundle branch block at hospital admission in patients with acute MI predicts in-hospital complications and poor short-term survival.

Isolated left posterior fascicular block: a reliable marker for inferior myocardial infarction and associated severe coronary artery disease

The electrocardiographic (ECG) pattern of isolated left posterior fascicular block (LPFB) is a rare condition. It seems that true LPFB is often not recognized, whereas in cases of simple QRS axis of +60 degrees to +100 degrees in the frontal plane, the diagnosis of LPFB is made erroneously. Both facts rely on controversial and partially misleading opinions in the literature. Therefore, a retrospective and prospective study was performed in order to determine the prevalence of LPFB and to correlate its presence to the underlying disease. Retrospective study: Of a cohort of 830 patients referred in 1988 to a cardiologic laboratory for invasive investigation of certain or suspected coronary artery disease (CAD), 163 patients had an old inferior myocardial infarction (IMI). Nine patients (5.5%) showed the typical pattern of LPFB; eight of these had three-vessel disease. The diagnosis of IMI had been made only in one case before entry of the patient into the hospital, since LPFB generally masks IMI. Prospective study: 2502 ECGs were investigated, 1710 from a department of cardiology and 792 from two departments of internal medicine. Six LPFBs were detected (0.24%), all associated with IMI and four of them with three-vessel CAD. It is concluded that LPFB is a rare but clinically important intraventricular conduction disturbance. Its appearance is reliably connected with IMI and generally reflects severe three-vessel CAD, requiring invasive investigation.