Abstract
Fractional flow reserve (FFR) measurement provides useful hemodynamic assessment of intermediate coronary stenoses affecting long term outcomes. While the gold standard remains intravenous adenosine, intracoronary (IC) bolus administration of adenosine is routinely used in clinical practice because of its ease of use and lower dose providing comparative hyperemia with the most common side effect being a transient atrioventricular block. A 62 year old male underwent left heart catheterization after ruling in for non-ST elevation myocardial infarction (NSTEMI). Presenting electrocardiogram (ECG) showed an old left bundle branch block and T-wave inversions in lateral leads (QTc 494 ms) with no significant electrolyte abnormalities. Coronary angiography revealed an intermediate lesion in mid left anterior descending coronary artery. FFR assessment with IC adenosine (24 μg/mL of normal saline) was performed inducing ventricular fibrillation (VF). He was successfully defibrillated with a single 200 J shock and no further arrhythmias were noticed during rest of his hospital stay.
Highlights
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Fractional flow reserve (FFR) measurement provides useful hemodynamic assessment of intermediate coronary stenoses affecting long term outcomes.
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Higher doses of IC adenosine could be as efficient as intravenous adenosine in obtaining maximum hyperemia and are considered to be relatively safe and well tolerated with the most common side effect being a transient atrioventricular block.
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Baseline clinical and electrocardiographic abnormalities have not proven to predict development of life threatening ventricular arrhythmias.
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It remains important to recognize potential complications and side effects associated with IC adenosine.
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Cardiac catheterization labs should be equipped and have protocols delineated to handle life threatening emergencies during routine diagnostic procedures.
1
Introduction
FFR assessment is an increasingly utilized tool in cardiac catheterization laboratories which provides useful hemodynamic assessment of intermediate coronary stenoses affecting long term outcomes . While the gold standard remains intravenous adenosine administration, IC bolus administration of adenosine is routinely used in clinical practice because of its ease of use, lower dose, and hence, overall cost. Recent data suggest that higher doses of IC adenosine could be as efficient as intravenous adenosine in obtaining maximum hyperemia and are considered to be relatively safe and well tolerated. We present a case of VF induced by IC adenosine during FFR assessment.
2
Case report
A 62-year-old male with significant history of active smoking over 25 years, peripheral arterial disease, cerebrovascular accident, hypertension and hyperlipidemia presented to emergency department with an acute worsening of intermittent exertional chest pressure radiating to left arm for a month and associated shortness of breath. His chest pain resolved upon arrival after chewable aspirin 324 mg and a single dose of 0.4 mg sublingual nitroglycerine. Blood pressure on presentation was 140/73 mmHg with a pulse of 70 bpm. He was euvolemic on physical examination and presenting ECG showed an old LBBB and T-wave inversions in lateral leads with a QTc interval of 494 ms and QRS duration of 136 ms ( Fig. 1 ). Pertinent admission laboratory data include a K + of 3.6 mmol/L (3.6 mEq/L), Mg of 0.78 mmol/L (1.9 mg/dL), NT-proBNP of 3254 ng/L and initial Troponin-I of <0.01 μg/L. He ruled in for a NSTEMI with a repeat Troponin-I of 0.7 μg/L and was started on intravenous heparin infusion along with a high intensity statin and a beta-blocker. Coronary angiography revealed a normal left main with mild non-obstructive disease in left circumflex and right coronary arteries. There were two lesions in the mid segment of the LAD, up to maximum 50% stenosis in multiple views ( Fig. 2 ). To assess their physiologic significance, FFR measurement was performed. Baseline FFR assessment decreased from 0.99 to 0.92 following administration of 72 μg (24 μg/mL of normal saline) of IC adenosine. In order to ensure maximal hyperemic response of the coronary bed, an additional 96 μg of IC adenosine was administered after two minutes, followed by fast normal saline flush. The patient went into polymorphic VT, degenerating into coarse VF immediately following the saline flush ( Fig. 3 ). He was successfully defibrillated with a single 200 J shock and remained hemodynamically stable for the rest of the procedure. Transthoracic echocardiogram obtained after the procedure showed moderately depressed left ventricular ejection fraction with global hypokinesis and no significant valvular abnormalities. No further arrhythmias were noticed for the remainder of his hospital stay.
